Fail at run time if Service uses an obsolete signal.

The threaded framework requires Services to switch to a new collection
of signals. To allow easier migration, the obsolete signals have been
replaced with a class which causes an Exception to be thrown if their
connect method is called.
Had to change one unit test which was making use of the old signals.
Merge pull request #1209 from Dr15Jones/throwObsoleteServiceAPI

Fail at run time if Service uses an obsolete signal.