Adding guest agent pkg unit tests and running them with testr

Added unit tests for reddwarf.guestagent.pkg module.
Added tests for package install, remove and version
Changing the test runner of unittests to be run by testr instead of probocis/nose
Remove probocis reference from the dbaas test
Moved dbaas.py to reddwarf/tests/unittests

tracked by bug #1090139

Change-Id: Ia25fbe996d04d39e83edef0369de0e7fccce579e