Update boot and cluster

Lots of fixes to the boot and cluster process:
- upgrade winston version
  - (but we need to explicitly set log levels until https://github.com/flatiron/winston/pull/290 is fixed
  - this fixes https://github.com/evantahler/actionHero/issues/210
- allow the app to boot if there are no active servers
- cleanup and simplification of the boot (start.js) wrapper
- fixes for when cluster workers would become unresponsive https://github.com/evantahler/actionHero/issues/200
- remove unneeded redis 'subscriber' connection