add numpy 1.8 nanfunctions to ensure np1.8 = np1.9 behavior
udpate tests
moments no longer uses np.nansum (np_compat.nansum instead)
don't convert to np.float - can double data size!  (very bad for large
cubes)
apparently data MUST be coerced to floating point unless it's already a
float.  I don't understand why.  Tests are still broken in a place I
don't understand
cleanup data[view]/dtype logic
add np 1.9 to travis as the default, with the expectation that this will
break everything
travis: more tests with 1.8 vs 1.9.  This will still fail, but at least
it shouldn't error