Adds voting support

This started as a server-side Rails app, but reached some limitations
with how I wanted it to be used without JavaScript.
Updates app to work with Rails 4.0.3 and Ruby 2.1.1
Refactor voting app to Ember.js

The initial server-side app had the data model I wanted, but I did not
like how it used one big form with a bunch of hacky view logic for the
actual voting process. This refactors it to an Ember.js app to make it
easier to add the voting features I wanted.
Dry-up IndexController.
adds message while proposals are loading
Use RSVP.hash to keep async in model hook.
Use quoted action names.

Using unquoted action names still works, but is deprecated (unless you
intend for it to be bound to a property of that name).
Pass needed values into toggleVote action.
Removes unused markdown gem

This was in the original rails implementation
Adds vote count widget to top of page
Merge pull request #32 from burlingtonruby/voting-ember

Adding voting support