Using volume/claim.UID in the operation name is not really useful, as UIDs
are not logged by rest of the controller. On the other hand, volume.Name and
claim.Namespace/Name is logged pretty often and it would help to log these
also in operation name.
This has been already proven to be very useful in controller debugging.
- remove persistentvolume_ prefix from all files
- split controller.go into controller.go and controller_base.go (to have them
under 1500 lines for github)