Tox based jobs for EventLogging

Trigger mwext-EventLogging-tox-flake8 instead of the pep8/pyflakes jobs.

Add unit tests to the test pipeline: mwext-EventLogging-tox-py27

We dont have python 3.3 so cant trigger them :(

Change-Id: Id9eb8f1e32f1c19b3faa9fc84fa36ee405bf1e1f