[Buildbot] #3287: Set up automated testing of buildslave on Python 3

[Buildbot trac]

#3287: Set up automated testing of buildslave on Python 3
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Reporter:  dustin       |      Owner:
    Type:  enhancement  |     Status:  new
Priority:  major        |  Milestone:  ongoing
 Version:  master       |   Keywords:
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 This basically entails running `trial buildslave.tests` on Py3.3, 3.4, and
 3.5.

 Let's start by running this in Travis (since that's self-serve), then port
 to metabuildbot.

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Ticket URL: <http://trac.buildbot.net/ticket/3287>
Buildbot <http://buildbot.net/>
Buildbot: build/test automation