Initial Styling

**Styling:**
* Add Bourbon, Neat, and Bitters
* Refactor navigation bar and `events#show` to use Refills components
* Style `events#show` with separate sections for event description, details, and reviews
* Use placeholder images next to reviews (to be replaced w/ more visual display of rating)
* Basic styling to display items on `events#index` in a grid

**Minor Presentation-Related Refactorings:**
* Rename "Media Review" to "Critic Review" in user-facing copy
* Extract helper method to format closing dates on `events#show`
* Refactor `event_preferences#create` JS to remove duplication
* Refactor `EventPreferencesHelper` to remove unnecessary `id` fields
* Extract helper method for rendering a user review score as stars

https://trello.com/c/PmjQfZUc

![screen shot 2014-08-29 at 10 37 31 am](https://cloud.githubusercontent.com/assets/7756801/4091585/3838e032-2f8a-11e4-9f1c-e5464495ade2.png)
![screen shot 2014-08-29 at 10 38 28 am](https://cloud.githubusercontent.com/assets/7756801/4091586/383c8e76-2f8a-11e4-913c-4cb6ee4cae74.png)