removes whitespace below a gallery that is a direct child of the last .container

Removes bottom padding on a gallery that is a direct child of the last .container:

![image](https://cloud.githubusercontent.com/assets/1566749/4292290/0f0f511e-3dcc-11e4-9e20-1a7c3ae52cd1.png)

Resolves [DS-400](https://jira.dosomething.org/browse/DS-400)