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.

The WindowsServiceHost is simply reused for convenience as it will function properly under linux (at least with the testing we've done).  It will be run when the service is started under linux using mono-service.exe.  If the service is started with mono.exe (as a console application rather than a service) it would not be run.