Added support for running the tests under PyPy with tox

This is a precursor to having them run under check and gate.

This also fixes a single test which fails on PyPy, the test failes at
because it assumes a ``dict`` has a particular order for its keys when
it is printed out, on PyPy dicts have a different order sometimes, the
exact ordering is not a guarnteed property of Python.

Change-Id: Ie86726a0221e5e9aa68f7303d8ca8c7acd878f65