Enhancements to reviewer dashboard

- Added a status dropdown menu to filter games by status, including logic to actually fetch the games matching the selected status
- Added buttons to view, edit, disable, and delete a game, using font-awesome icons and CSS tooltips to de-emphasize them somewhat
- Hooked up the delete / disable buttons to update the game's status accordingly
- Reworked style to match the mockups

This is what the page now looks like:

![](http://cl.ly/image/2N1q3j0d2Y3w/Image%202014-03-18%20at%205.26.44%20PM.png)

Other minor changes:

- Updated `dates.js` to append the "ago" suffix to relative dates, per the mockups
- Enhanced the `date` nunjucks filter in `helpers.js` to support short month names through the `med` option
- Added a `nocache` option to the `defer` nunjucks extension, which prevents use of the cache for that request (needed for the reviewer dashboard because the list of games under a given status can and will change, especially if the reviewer changes the status of a game themselves)
- Refactored the button colour styles in `buttons.styl` to use a mixin that reduces duplication, and added a `btn-disable` class for the disable button in the reviewer dashboard

@cvan Please let me know if changes to commonplace files are not kosher and I can figure out alternatives for some of the above changes.

There are still a couple of things left to be done that I figured could be done in a separate pull request:

- The view and edit buttons don't do anything yet
- The buttons displayed are the same regardless of the selected status (so the approve button is still shown in the list of approved games for example, which is definitely weird)

This pull request is somewhat dependent on #113 (since it refactors `review.styl` into a shared `dashboard.styl`), which will necessitate an ugly merge when it's done.

Fixes #121, #122, #123.