* As a side effect the bug related to oslo.messaging (AttributeError: ...)
was also fixed by moving monkey patching to mistral/__init__.py. Monkey
patching has to be done before importing oslo.messaging. Details can be
found at https://bugs.launchpad.net/oslo.messaging/+bug/1288878
* Refactored environment engine tests
* Refactored and fixed environment API tests (there was a number of
fragile dict string representation comparisons)
Closes-Bug: #1337705
Change-Id: Id725570dfc7148f010647c4b2487882174b0c56e