Dont keep reforking forever

[JesseCrocker]

Dont keep reforking forever, because we dont want an infinite loop.
Also fixes logging to correctly log PID of old process.

[JesseCrocker]

Logs when using this, with worker count set to 2

orker_1              | Launching tilesquirrel with config /opt/tilesquirrel-dev.json
worker_1              | + node --max-old-space-size=1024 /opt/tile-squirrel/bin/squirrel.js -d -r tilejsonHttpShim -r tilelive-s3 -c /opt/tilesquirrel-dev.json
worker_1              | Starting worker
worker_1              | Starting worker
worker_1              | module.js:550
worker_1              |     throw err;
worker_1              |     ^
worker_1              |
worker_1              | Error: Cannot find module 'tilelive'
worker_1              |     at Function.Module._resolveFilename (module.js:548:15)
worker_1              |     at Function.Module._load (module.js:475:25)
worker_1              |     at Module.require (module.js:597:17)
worker_1              |     at require (internal/module.js:11:18)
worker_1              |     at module.exports (/opt/tile-squirrel/lib/cacher.js:12:18)
worker_1              |     at run (/opt/tile-squirrel/bin/squirrel.js:85:29)
worker_1              |     at Object.<anonymous> (/opt/tile-squirrel/bin/squirrel.js:59:12)
worker_1              |     at Module._compile (module.js:653:30)
worker_1              |     at Object.Module._extensions..js (module.js:664:10)
worker_1              |     at Module.load (module.js:566:32)
worker_1              | module.js:550
worker_1              |     throw err;
worker_1              |     ^
worker_1              |
worker_1              | Error: Cannot find module 'tilelive'
worker_1              |     at Function.Module._resolveFilename (module.js:548:15)
worker_1              |     at Function.Module._load (module.js:475:25)
worker_1              |     at Module.require (module.js:597:17)
worker_1              |     at require (internal/module.js:11:18)
worker_1              |     at module.exports (/opt/tile-squirrel/lib/cacher.js:12:18)
worker_1              |     at run (/opt/tile-squirrel/bin/squirrel.js:85:29)
worker_1              |     at Object.<anonymous> (/opt/tile-squirrel/bin/squirrel.js:59:12)
worker_1              |     at Module._compile (module.js:653:30)
worker_1              |     at Object.Module._extensions..js (module.js:664:10)
worker_1              |     at Module.load (module.js:566:32)
worker_1              | worker 47 died and has been replaced by 59
worker_1              | worker 48 died and has been replaced by 65
worker_1              | Starting worker
worker_1              | Starting worker
worker_1              | module.js:550
worker_1              |     throw err;
worker_1              |     ^
worker_1              |
worker_1              | Error: Cannot find module 'tilelive'
worker_1              |     at Function.Module._resolveFilename (module.js:548:15)
worker_1              |     at Function.Module._load (module.js:475:25)
worker_1              |     at Module.require (module.js:597:17)
worker_1              |     at require (internal/module.js:11:18)
worker_1              |     at module.exports (/opt/tile-squirrel/lib/cacher.js:12:18)
worker_1              |     at run (/opt/tile-squirrel/bin/squirrel.js:85:29)
worker_1              |     at Object.<anonymous> (/opt/tile-squirrel/bin/squirrel.js:59:12)
worker_1              |     at Module._compile (module.js:653:30)
worker_1              |     at Object.Module._extensions..js (module.js:664:10)
worker_1              |     at Module.load (module.js:566:32)
worker_1              | worker 59 died and has been replaced by 71
worker_1              | module.js:550
worker_1              |     throw err;
worker_1              |     ^
worker_1              |
worker_1              | Error: Cannot find module 'tilelive'
worker_1              |     at Function.Module._resolveFilename (module.js:548:15)
worker_1              |     at Function.Module._load (module.js:475:25)
worker_1              |     at Module.require (module.js:597:17)
worker_1              |     at require (internal/module.js:11:18)
worker_1              |     at module.exports (/opt/tile-squirrel/lib/cacher.js:12:18)
worker_1              |     at run (/opt/tile-squirrel/bin/squirrel.js:85:29)
worker_1              |     at Object.<anonymous> (/opt/tile-squirrel/bin/squirrel.js:59:12)
worker_1              |     at Module._compile (module.js:653:30)
worker_1              |     at Object.Module._extensions..js (module.js:664:10)
worker_1              |     at Module.load (module.js:566:32)
worker_1              | worker 65 died and has been replaced by 77
worker_1              | Starting worker
worker_1              | Starting worker
worker_1              | module.js:550
worker_1              |     throw err;
worker_1              |     ^
worker_1              |
worker_1              | Error: Cannot find module 'tilelive'
worker_1              |     at Function.Module._resolveFilename (module.js:548:15)
worker_1              |     at Function.Module._load (module.js:475:25)
worker_1              |     at Module.require (module.js:597:17)
worker_1              |     at require (internal/module.js:11:18)
worker_1              |     at module.exports (/opt/tile-squirrel/lib/cacher.js:12:18)
worker_1              |     at run (/opt/tile-squirrel/bin/squirrel.js:85:29)
worker_1              |     at Object.<anonymous> (/opt/tile-squirrel/bin/squirrel.js:59:12)
worker_1              |     at Module._compile (module.js:653:30)
worker_1              |     at Object.Module._extensions..js (module.js:664:10)
worker_1              |     at Module.load (module.js:566:32)
worker_1              | worker 71 died and has been replaced by 83
worker_1              | module.js:550
worker_1              |     throw err;
worker_1              |     ^
worker_1              |
worker_1              | Error: Cannot find module 'tilelive'
worker_1              |     at Function.Module._resolveFilename (module.js:548:15)
worker_1              |     at Function.Module._load (module.js:475:25)
worker_1              |     at Module.require (module.js:597:17)
worker_1              |     at require (internal/module.js:11:18)
worker_1              |     at module.exports (/opt/tile-squirrel/lib/cacher.js:12:18)
worker_1              |     at run (/opt/tile-squirrel/bin/squirrel.js:85:29)
worker_1              |     at Object.<anonymous> (/opt/tile-squirrel/bin/squirrel.js:59:12)
worker_1              |     at Module._compile (module.js:653:30)
worker_1              |     at Object.Module._extensions..js (module.js:664:10)
worker_1              |     at Module.load (module.js:566:32)
worker_1              | worker 77 died. Not starting a new worker because of too many failures.
worker_1              | Starting worker
worker_1              | module.js:550
worker_1              |     throw err;
worker_1              |     ^
worker_1              |
worker_1              | Error: Cannot find module 'tilelive'
worker_1              |     at Function.Module._resolveFilename (module.js:548:15)
worker_1              |     at Function.Module._load (module.js:475:25)
worker_1              |     at Module.require (module.js:597:17)
worker_1              |     at require (internal/module.js:11:18)
worker_1              |     at module.exports (/opt/tile-squirrel/lib/cacher.js:12:18)
worker_1              |     at run (/opt/tile-squirrel/bin/squirrel.js:85:29)
worker_1              |     at Object.<anonymous> (/opt/tile-squirrel/bin/squirrel.js:59:12)
worker_1              |     at Module._compile (module.js:653:30)
worker_1              |     at Object.Module._extensions..js (module.js:664:10)
worker_1              |     at Module.load (module.js:566:32)
worker_1              | worker 83 died. Not starting a new worker because of too many failures.