Fixed alignment of download dropdown

## What does this MR do?

Correctly aligns the download dropdown on merge requests

## Screenshots (if relevant)

![Screen_Shot_2016-06-14_at_14.47.06](/uploads/9381f25110e5573e56aa5c3f46786df5/Screen_Shot_2016-06-14_at_14.47.06.png)

See merge request !4646