OS X binstar recipe.

Add a binstar recipe for OS X. Please check the naming convention (just replaced linux-64 by osx, not sure whether that is correct, couldn't find the docs with 5min effort).

The builds seem to work fine on my machine, if I can be of help uploading them to the statsmodels binstar channel, please let me know how.

Btw, having them up there around the middle of the month would save me a bunch of install headaches for a course I'm teaching...