PY3 make it possible to run some tests in Python3

* switch to Twisted 14.0.0 because SVN version broke twisted.log in Python 3;
* skip top-level shortcuts to make at least some tests pass;
* use PY3 compatible import of _monkeypatches.
Merge pull request #776 from kmike/py3-tests-fix

PY3 make it possible to run some tests in Python3