PEP 8 cleanup.
Merging in the fix from @akinfold as well as another that was giving a
bug on relationships.clear() due to a missing 'through'...good to go
passing on 1.3 and 1.4
Test runner should be compat with 1.3 and 1.4
Allow running tests with postgres
Shuffling the tests around to make for easier testing, and adding test
runner to setup.py