Revert "Remove UIActionSheetRACSupportSpec"

This reverts commit c9ba5a5e39cc168275ce37e96ac3f016ab74a09f.

Conflicts:
	ReactiveCocoaFramework/ReactiveCocoa.xcodeproj/project.pbxproj
Test by invoking UIActionSheetDelegate method directly

Testing the full input->output path, from UI to delegate method, would be nice,
but not strictly necessary since that's testing Apple's code. Either way, this
is better than nothing.
Merge pull request #707 from ReactiveCocoa/uiactionsheet-tests

UIActionSheet tests redux