Merge setup3-same-classifiers-7333

Author: exarkun (sponsored by Hybrid Logic, Ltd.)
Reviewer: khorn
Fixes: #7333

Remove the trove classifier override in the Python 3 distutils entrypoint.
This makes the classifiers consistent whether Python 2 or Python 3 is being
used.


git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/trunk@43059 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb