ove_2#21665 - Fixing test unit tests for Deeptest
ove_2#21665 - Adding graceful shutdown of central command

This should ensure that any agents running on the remote machines
terminate gracefully after receiving the "NoWorkRemaining" message
instead of Central Command terminating and letting Agent processes die
leaving an orphaned beachhead zombie process.
Adding agent ending callback for agent cleanup.

This callback on the listener interface should replace the
interception of the agent process on exit to run any cleanup
logic. Using the at_exit block, while in theory should work, seemed
to be having issues possibly due to the process being killed
unexpectedly. This fix skirts around the issue a little bit but in
general it doesn't seem necessary to run this cleanup in an on_exit
block.
Removing trap of sig term on agents

Trapping the SIGTERM to ensure a graceful exit seemed
more necessary when we were doing a lot of our agent cleanup
on the at_exit block for the agent process. Given we're no longer
doing that, and instead cleaning up on an ensure block, our process
will die gracefully even when it receives a SIGTERM.
Adding the ability to build as a gem
Updating .gitignore