Upgrade Ruby, Rails

So, I think we should upgrade to the latest versions of everything. For speed, for safety, and for our sanity later.

Pull this and try it and let me know what you think. If you'd prefer I push it to heroku, I will, but I would prefer if you did it.

To upgrade from the heroku bamboo stack to the cedar stack (which we should),
https://devcenter.heroku.com/articles/cedar-migration

I created a new heroku app to test it -- everything seems to be peachy:
http://hvz-test.herokuapp.com