Add backbone rails gem to project

This commit adds backbone to the project via a gem.

It's not being used yet, but this is in preparation for creating a more
JS-focused experience particularly for the map.
Replace area JS with backbone view

This commit moves the area.js javascript code into a new backbone view.

This is the JS that handles clicks on an area map.
Make map checkins load via AJAX

This commit makes it so that when you checkin on the area zone map, the
zones will load via AJAX instead of the whole page reloading.

This is done via a new zones partial and a XHR endpoint in the areas
controller.
Move home helper methods into appropriate helpers

Previously there were a few helper methods in the home helper which are
no longer related to the home page. This commit moves each function into
its respective helper.
Emphasize current user avatar on the map

The current user is now identified with a 'me' CSS class. This is used
to change the avatar color slightly so that you can identify yourself
more easily.

It will also be used to hook onto the current user in JS.
Add global loading indicator

This commit adds a global loading bar which can be triggered from
anywhere in the app. Basically you just tell it when to start and stop
and it will manage multiple loading requests.

Other changes include a fix to the AJAX zone refreshing. The backbone
views weren't distinct and checking in to one area did not refresh the
other area, that's now fixed.