Clean up

- use the Rails logger rather than create a sepaerate logger
- remove suppresion of log output in various modules
- remove log subscription patches
- remove unneeded patches
- decouple log device from event payload
- create a message processor in the logger class that can handle a string, hash, or
  exception

The gem is now mostly about instrumentation, but also provides a JSON logger that abides by the logstash "standard" format.  You need not need use instrumentation if you simply want logstash style logs, but both together are handy in a typical rails project.