Properly make a request a POST for a test
Support for pyfilesystem field (and minor PEP8+test cleanups)
Merge pull request #21 from edx/pmitros/pyfilesystem-refactor

Pyfilesystem support. Also: 
* Support for XBlocks refactor
* PEP8 fixes
* Fix for one failing test-case from Ned. 
* Selenium test (workbench.test.test_problems.ProblemInteractionTest) is still intermittent. Works on my machine. Sometimes works on Travis, sometimes fails.