Rename -addSignalBlock: to -addDeferredSignal:
Reinstate -addSignalBlock: as a deprecated method
Catch and redirect deferred signal errors
-addDeferedSignal: > -addActionBlock:
Merge branch '2.0-development' into catch-command-errors

Conflicts:
	ReactiveCocoaFramework/ReactiveCocoa/RACCommand.h
	ReactiveCocoaFramework/ReactiveCocoa/RACCommand.m
Merge pull request #530 from ReactiveCocoa/catch-command-errors

Rename -addSignalBlock: to -addDeferredSignal:, hide errors from subscribers