Support for starting/stopping application from linux command line using mono-service.exe

Allows user to start application using mono-service.exe and have proper start/stop behavior.
In our testing, unless IsRunningAsAService was true, TopShelf would not execute the Service.WhenStopped action.  This was true even when we used mono-service.exe (as in your example).  Stopping the service did end the application process but seemed to terminate the application immediately without running the Service.WhenStopped action.  I believe under Windows, when running in console mode, TopShelf monitors the process and runs the Service.WhenStopped action for you upon termination.  Under linux, that process monitoring is handled by MonoServiceRunner and depends on the app being run as a service.