now listening to Unix Signals to exit gracefully

[mkobaly]

When running a mono application using docker the container and trying to stop the container it would take a while to exit and return with a non zero exit code.

LinuxConsoleRunHost is a copy of ConsoleRunHost from Topshelf with the UnixSignal support. LinuxRunBuilder is copy of RunBuilder from Topshelf where the LinuxConsoleRunHost is used.

[mkobaly]

I will update the pull request.