added Jena transaction abort, for when a deposit job throws an error. Updated commit method name to match.
removed some local strings from DepositGenerator
added error handling for 400 Bad Request to IngestController (from upstream Sword servlet) this handles duplicate deposit requests
removed secondary wrapping of SwordError exceptions in another exception.
Merge pull request #169 from UNC-Libraries/bagit-resque-dupe-deposit

Prevent duplicate METS deposit, Jena transaction fix