Something is broken in pip so it installs a wrapt that doesn't support
Python 3.4. Work around this by manually request a version that is known
to work.
Travis are dropping older Python environments, so update things to
something that reflects what current distributions are using (e.g. Red
Hat Enterprise Linux 7).
mox is pretty much unmaintained these days, however the OpenStack
project are actively maintaining mox3 (a Python 3 compatibile fork
with some other improvements).
websockify seems quite happy to use mox3 instead, so switch the
test dependency and associated imports to use mox3.
This commit enables running the unit tests on Travis for Python 2.6,
2.7, 3.3, and 3.4. Note that Travis does not support Python 2.4, so
we cannot test there.
Javier Cacheiro