902869 - more robust handling of --force unregistration.
discontinue catching socket exceptions since handled by framework.
use exceptions CODE_ instead of os.EX_ codes where possible.
use exceptions CODE_ instead of os.EX_ codes where possible.
Use CODE_PERMISSIONS_EXCEPTION
Invert forced flag logic.  Seems less explicit but .. guess it's simpler.
Merge pull request #369 from pulp/jortel-902869

902869 - more robust handling of --force unregistration.