This patch implements the majority opinion from issue24391 for the desired format of the reprs produced by Event, Semaphore, BoundedSemaphore, and Barrier.  It provides tests around each, inspired by Serhiy's preliminary patch for that same issue but adapted for multiprocessing.

These tests pass on all but 2 -- it is expected that those 2 will pass once the threading module has been similarly updated as some of the combinatoric tests leverage threading.Event in some cases and multiprocessing.Event in others (and so on for the other synchronization objects).  At present, Serhiy's patch still needs updating to match the majority opinion on the repr format, hence it could not yet be applied in combination with this patch for testing.  Tests thus far have been performed on OS X 10.10.3.