Fix up python 3.3 incompatabilities

Make the python 3.3 testing work by selectively
disabling & including eventlet, switch to testtools
and testrepository which has 2.6, 2.7, 3.2+ unified
testing support so that we can correctly run our
tests in all supported python versions.

Closes-Bug: #1251660
Co-authored-by: Alexander Gorodnev <agorodnev@griddynamics.com>
Change-Id: I23b6f04387cfd3bf6b5a044edffa446ca897ce3a