Change logging to less verbose

Currently logging looks like this:
```
worker.1 | [11] Running wp cavalcade run 11 (wp_scheduled_auto_draft_delete a:0:{})
worker.1 | [11] Started worker
worker.1 | [11] Worker status: Array
worker.1 | (
worker.1 | [command] => wp cavalcade run 11
worker.1 | [pid] => 52
worker.1 | [running] =>
worker.1 | [signaled] =>
worker.1 | [stopped] =>
worker.1 | [exitcode] => 0
worker.1 | [termsig] => 0
worker.1 | [stopsig] => 0
worker.1 | )
worker.1 |
worker.1 | [11] Worker shutting down...
worker.1 | [11] Worker out:
worker.1 | [11] Worker err:
worker.1 | [11] Worker ret: 0
```

Could we just log one line like nginx? I had something like this in mind:
```
[11] [28/Jul/2017:14:43:41 +0000] START wp_scheduled_auto_draft_delete a:0:{}
[11] [28/Jul/2017:14:43:45 +0000] END wp_scheduled_auto_draft_delete 0 ["output"] ["error text"]
```

No files, tests, or entry points are identified in the issue. Start by locating the worker logging that produces the shown command, status, output, and error lines; compare its lifecycle with the proposed START and END format. Done means job execution is represented by concise timestamped lines while retaining the command, return status, output, and error information.

Written by the indexing model from the issue text.