gst/: remove the hash table for miniobjects - since we can't get notified when they get destroyed, we shouldn't be ca...

Original commit message from CVS:

* gst/gst.override:
* gst/pygstminiobject.c:
remove the hash table for miniobjects - since we can't get notified
when they get destroyed, we shouldn't be caching pointer mappings
* testsuite/test_pad.py:
update refcount tests because mini objects now have a ref for
each time an object is made for it