Updaing libraries/removing rubyracer

Hello! Not sure is this is an active project or not, but I'm loving it. I've updated the backbone, underscore, and jquery libraries to the most recent versions (1.0.0, 1.4.4, 1.9.1, respectively). I've also updated twitter bootstrap to v 2.3.1.

Also, the ruby racer gem seems to be depreciated; so I removed it from the gem file.

Here's a pull request if you want to merge some or all of these changes in.

Thanks for making such a helpful collection!