Voting

Allow for AJAXy voting on comments and articles. Resolves #14.


![](http://zippy.gfycat.com/ImpracticalPastCardinal.gif)
Probably render any errors on `@vote` on the current page. Probably something like:
```
# votes_controller.rb
format.js { render template: 'votes/vote_errors' }
```
```
# votes/vote_errors.js.erb
$("#articles").prepend('<%= escape_javascript(render 'shared/form_errors', object: vote) %>');
```