Front-end automations

Adds Susy 2 alpha 2 for Rails 4 (see http://oddbird.net/2013/05/03/susy-next-alpha-2/)
Adds guard listener to automagically install new gems
Adds Compass 2 alpha for Rails 4 support
Adds a really simple grid from susy (using the new syntax) to ensure the library is working
Adds a content wrapper around the layout