OmeroPy threads should not be called "dummy"

[jamoore]

For some reason, Ice initializes the thread pool under Python to "dummy-".

[jmoore]

This isn't an Ice issue, but is hard-coded in threading.py:

# Dummy thread class to represent threads not started here.
# These aren't garbage collected when they die, nor can they be waited for.
# If they invoke anything in threading.py that calls current_thread(), they
# leave an entry in the _active dict forever after.
# Their purpose is to return *something* from current_thread().
# They are marked as daemon threads so we won't wait for them
# when we exit (conform previous semantics).

class _DummyThread(Thread):

    def __init__(self):
        Thread.__init__(self, name=_newname("Dummy-%d"))