Don't use patched Thread._stop with python > 2.7 or 3.2
Drop support for Thread._stop patch on Python 3.0 and 3.1

Those versions of Python are not supported by Circus, so we don't
need to have special patches for them.
Merge pull request #844 from k4nar/join_thread_issue

Don't use patched Thread._stop with python > 2.7 or 3.2