MAINT: clean up comments/commented-out code in distributions.py; some PEP8 fixes.
MAINT: enable rdist._cdf, making it a lot faster.  Closes gh-1285.

Issue for hyp2f1 that is worked around is discussed in gh-1561.
ENH: add central moment methods to invweibull and loglaplace distributions.

Faster, more accurate and removes a warning generated by the distribution fit
test for invweibull.
TST: speed up stats tests some more, and add run_module_suite to each test file
Merge pull request #2612 from rgommers/stats-distributions-cleanup

MAINT: clean up comments/commented-out code in distributions.py
BLD: Monkeypatch numpy.distutils to disable Accelerate's LAPACK part

The LAPACK bundled with Accelerate on OSX 10.7+ makes ARPACK produce
invalid results in some cases. This commit disables linking with the
Accelerate framework or the LAPACK component, but allows linking with
the BLAS one.