252 superfish

This pull request, created on top of Thomas' #234, restores the look of Shifts. This is achieved by re-integrating some of the old CSS stylesheets back into rails-3.2. There are two remaining front-end issues, both related to the not-yet-functional superfish.js:
1. The menu item on the navigation bar that contains sub-menus are missing a downward arrow
2. The sub-menu animation is not working. Right now the sub-menus just appear.
However, this is a working version of the navigation bar with the correct styling, so I created this pull request.
This pull request also moves all the JavaScripts under vendor/ to vendor/assets/javascripts.
We are thinking about getting rid of superfish altogether and use bootstrap instead for the menus.