Feature/clean blog layout

- Adds font awesome and replaces twitter/rss/github icons with those to improve sizing consistency. Also closes #419.
- Adjusts h3 spacing in blog posts -- gives it a bit more breathing room
- Cleans previous and next post styles, and responds to user feedback that the entire block should be clickable rather than just the blog post title
- Adds related links code and styles, and therefore incorporates PR #372 . Note: I changed the # of posts displayed from 5 to 3. 5 seemed like overkill and cluttered the space.
- Moves 'back to blog' link to top of page to match implementation on Dashboard project pages
- Adds space to top of bare template to compensate for the addition of the 'official usa' bug
- Cleans 'follow us' links at bottom of blog posts
- Removes github link from follow us - seems unnecessary at the bottom of blog posts to ask people to follow us for news at github

## Top of page
![screenshot 2014-12-24 11 31 03](https://cloud.githubusercontent.com/assets/4827522/5550424/babe5cec-8b62-11e4-94ca-ad7a38191175.png)

## Bottom of page
![screenshot 2014-12-24 11 43 25](https://cloud.githubusercontent.com/assets/4827522/5550425/bf09ba80-8b62-11e4-83a0-105689593f45.png)