Cap Petschulat

Running `CC=clang PYDISTRIBUTIONS_USE_LIB=1 make test` on OSX, I see these errors: ``` ====================================================================== FAIL: distributions.tests.test_clustering.test_models(, 5) ---------------------------------------------------------------------- Traceback (most recent call last): File "/Users/cpetschulat/.virtualenvs/pk/lib/python2.7/site-packages/nose/case.py", line 197, in runTest self.test(*self.arg) File...