Python 3.3 and 3.4 compatibility

Updated tox testing, and wercker configuration, required fixing of available connectors
since gevent is not compatible with python 3.x.

Bytearrays have to be handled correctly for python 3.x, the msgpack Unpacker by default
will return bytearrays in python 3.x and strings in python 2.x

using different wercker box base with python 3.3 and 3.4 installed