import exceptions to WorkQueueManager

@ticoann @hufnagel @amaltaro

This was founded out testing 0.9.95b.patch2 with newest sql alchemy and Oracle database.

```
2014-08-25 14:17:44,927:ERROR:WorkQueueManagerWMBSFileFeeder:Error in wmbs inject loop: No module named exceptions
2014-08-25 14:17:44,927:ERROR:BaseWorkerThread: Thread WorkQueueManagerWMBSFileFeeder:  Transaction reached
                                              end of poll loop. Raise a bug against me. Rollback.
```