[Merge] ~rikmills/unity:master into unity:master

[Rik Mills]

Also in #ubuntu-desktop <Trevinho> stated "I'm all fine with that, as per the testing side can probably all be removed safely" regarding the dep drop and removal of window-mocker source. It just so happens that in the meantime someone else did that upload dropping python2 and qt4.
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https://code.launchpad.net/~rikmills/unity/+git/unity/+merge/378891
Your team Unity Team is requested to review the proposed merge of ~rikmills/unity:master into unity:master.