CI: osx stack testing

[jreback]

seems that we could piggy back on this for testing on OSX, not sure how difficult this is

https://groups.google.com/forum/#!topic/pydata/Urr55F8b-eU

[jreback]

@TomAugspurger I believe you have OSX interest?

[TomAugspurger]

Yeah. I'll research this later

[jreback]

This is a link to the pretty automated builder that Matthew Brett built to create the OSX wheels. Using it on releasing now: https://groups.google.com/forum/#!topic/pydata/Bx8oiSAZwOc