Increase font size of media headings on home page.

Closes #936 

### Before
![before](https://cloud.githubusercontent.com/assets/96776/4361254/bec58d0c-4282-11e4-944d-d60a80b30573.png)

### After
![after](https://cloud.githubusercontent.com/assets/96776/4361255/bee2e3e8-4282-11e4-928b-5051842a2a71.png)