Update git-server and ssh-credentials dependencies
Fix findbugs null pointer exception warnings

The @CheckForNull annotation clarified some of the places where a null
pointer check is a useful check.  This resolves those warnings
Correct an exception message
Merge pull request #111 from MarkEWaite/master-findbugs-fix-NPE-warnings

Master findbugs fix npe warnings
Merge pull request #110 from MarkEWaite/master-update-dependencies

Update git-server and ssh-credentials dependencies