Error on ST3 for pretty_results due to Python 3

[barronbud]

On SublimeText 3, running tests generates this error:

can't use a string pattern on a bytes-like object

It seems to be related to the switch to Python 3.3 for ST3. The relevant line of code is at https://github.com/mxunit/sublime-text-2-mxunit/blob/master/mxunit_plugin.py#L246.

Changing json.loads(test_results) to json.loads(test_results.decode()) seems to resolve issue.