Return the correct host for git@ URLs

[cookpete]

Fixes #10

Node's built in url function doesn't seem to return the correct host for git@* urls:

λ node -e "console.log(require('url').parse('git@gh.pages.com:assemble/verb.git'))"
Url {
  protocol: null,
  slashes: null,
  auth: null,
  host: null,
  port: null,
  hostname: null,
  hash: null,
  search: null,
  query: null,
  pathname: 'git@gh.pages.com:assemble/verb.git',
  path: 'git@gh.pages.com:assemble/verb.git',
  href: 'git@gh.pages.com:assemble/verb.git' }

But it does if you stick a valid protocol in front:

λ node -e "console.log(require('url').parse('http://git@gh.pages.com:assemble/verb.git'))"
Url {
  protocol: 'http:',
  slashes: true,
  auth: 'git',
  host: 'gh.pages.com',
  port: null,
  hostname: 'gh.pages.com',
  hash: null,
  search: null,
  query: null,
  pathname: '/:assemble/verb.git',
  path: '/:assemble/verb.git',
  href: 'http://git@gh.pages.com/:assemble/verb.git' }

This PR checks if host is empty and the URL start with git@ and parses the URL with http:// prepended, to give us the correct host.

Tests added, and all existing tests pass.

[jonschlinkert]

published and released as 1.0.1, thanks!