New release message styling, and video release messaging copy

- Refactor Message object and template
- Refactor generic styles for messages
- Add message on Video pages

### Screen shots

#### Tablet
![google chrome](https://cloud.githubusercontent.com/assets/80089/3826086/e18ad810-1d5c-11e4-88a4-baf77e151338.png)

#### Desktop
![google chrome](https://cloud.githubusercontent.com/assets/80089/3826089/e9071ed2-1d5c-11e4-9fea-0ef9b37d96b6.png)

#### Wide
![google chrome](https://cloud.githubusercontent.com/assets/80089/3826092/ed170122-1d5c-11e4-806b-b03483b06afb.png)


/cc @rich-nguyen @mattosborn 



Hmm, actually between nested elements and `@include mq` I think there should be a newline.