Add an unregister repair option
Add an unregister repair option

Added a parser and function to unregister repair scripts. Remove
the repair script from the backend repair cfg, and watchdog will
catch it in the engine.

Change-Id: I7b93ca7e5eb4430b7c9502c8dd84af75b2a9fae3

stackforge/entropy,stackforge/entropy,stackforge/entropy