Merge pull request #11 from yetty/master

Fix submit_job to work with namespaces
Reusing existing client in submit_job wrapper.
Merge pull request #12 from yetty/master

worker_class (possibility of custom worker class instead of HookedGearmanWorker)
Cleanup for version 0.4.0.
Support for self terminating gearman worker.
Version bump 0.5.0.
Version bump to 0.6.0.
Fixed dependancy link.
_invoke_job: always return result instead of `OK`