Assets to rackspace

This PR sets up `rake assets:precompile` to sync assets to our Rackspace containers. It also points asset paths to the ones stored on Rackspace for production.
Although there's a `.env.sample` file, it'd be nice to have a comment in the REAMDE about how to setup things for new devs. It's easier to add this stuff in incrementally than having to do it as a huge exercise later. :)

(BTW, if `bin/setup` is meant to do just that, note that it copies `.sample.env` and not `.env.sample` over to `.env` :wink: )