Registration & Registered endpoints finished

The basic set of functionalities for both registration & registered containers is finished.

The plan was to cover the use cases and find out potential problems. 
Most important improvements and changes:
-direct interaction with irods backend (for b2safe staring replication step)
-using queue to pass commands to registration workers
-epic client extended to talk to both epic @ sara and handle.net (later required for requesting already registered files)