Slider menu

*** For discussion only, don't merge this yet ***

1) I added a js menu that slides open and pushes content to the right. It is available when user is signed in only. 
2) I also added functionality that changes the user's root path depending whether they're logged in or not. If logged in root_path == dashboard_path. 
3) In order for a user's session to remain persistent across subdomains, I added some configuration to the config/initializers/session_store.rb file. Everything works in production but it causes some of the tests to break. 

We need to figure out how to test this.