Watchfile

If the `watchr` gem is installed, then running `watchr Watchfile` will automatically runs all unit tests whenever source code changes. There are four watches set right now:

1) Run AppController unit tests whenever a Ruby source file changes in that folder.
2) Run Neptune unit tests whenever a Ruby source file changes in that folder.
3) Run AppDB, lib, and AppManager tests whenever a Python source file changes in those folders.
4) Run InfrastructureManager tests whenever a Python source file changes in those folders.

Adding these watches also reveals that unit tests are broken on the AppDB side, and that the InfrastructureManager tests are extremely slow to run (12 sec), but those are outside of the scope of this pull request.