Simplify bosh-monitor stop

* Remove exit(1) from Signal.trap because it will be 130 either way
* Remove soft=false from #stop because it was just for a test
* Remove EM.stop which will happen anyway because we're exiting the process
  and have nothing more to do once it has stopped

Signed-off-by: Adam Stegman <astegman@pivotallabs.com>