Remove unused py33 tox env

It's apparent that elastic-recheck is quite a ways from Py3K
support, and developers are not expected to run the py33 tox env.
Rather than add more envs for later Python interpreter versions
which will be equally broken, just remove it for now.

Change-Id: I6fb62f55d39eb812c585c19f9e16c482775f793a
Merge "Remove unused py33 tox env"