Jawns controller, actual hashing of Spark content

Also cleaned up the web directory, removing unnecessary helper files and putting needed ones in the correct spots.

The Jawns controller should now be accessable at `/api/v1/jawns.json?limit=n`, and it will return the most recent n sparks or ideas. I also added some tests to confirm that this works as expected.

I really need to work on the readme...sorry Sam!

BC, this pull request should be ready to push up to heroku. I did change the database though, so make sure to re-run `rake db:migrate` on the heroku side.