Mis-encoded UTF-8 characters in differential log results

[NickTitle]

Bug report

What operating system and version are you using?

 version = 10.13.6
   build = 17G65
platform = darwin

What version of osquery are you using?

3.3.0, plus 2.11.2 to validate findings

What steps did you take to reproduce the issue?

run this config and tail logs

{
  "options": {
    "logger_plugin": "filesystem",
    "logger_path": "logs/",
    "utc": "true"
  },
  "schedule": {
    "emoji-test-pack": {
      "query": "SELECT '🚲', unix_time from time",
      "interval": 5
    }
  }
}

What did you expect to see?

results including correctly-encoded unicode characters

What did you see instead?

results including mis-encoded unicode characters (actual output below)

{
  "name": "emoji-test-pack",
  "hostIdentifier": "🚲",
  "calendarTime": "Fri Nov  9 20:58:00 2018 UTC",
  "unixTime": 1541797080,
  "epoch": 0,
  "counter": 0,
  "columns": {
    "'🚲'": "\\xF0\\x9F\\x9A\\xB2",
    "unix_time": "1541797080"
  },
  "action": "added"
}

[NickTitle]

#520 looks like it ran into something similar way back in Dec 2014

[obelisk]

Yeah this has been a thing for a long time but I'm not sure how complex the fix is. It could be that this is something osquery is doing during serialization (making the fix probably quite easy) or it could be happening in RocksDB (though I think this less likely) and be much harder to fix.

I think the real motivation for a fix here will be the failure to render Chinese/Japanese characters correctly.