Bourbon

Start styling with Bourbon.

This is as much an excuse to get practice with Bourbon as anything. Right now only the sass infrastructure and navbar are done.

@andrewhouse - I'll be glad to finish up the body styling myself if you don't want to, but do take a look through the PR. I ended up tweaking some of the routes while working on the navbar and added some comments inline in the process (they should all have a # NB before them).

If you're happy with this change, please merge in and deploy to Heroku.