Re-prioritize Submission Button CSS.

Right now on the edit submission page the primary button is the one that goes back to the previous page. The primary button should be the save button to save any submissions you may have edited.

I also changed `Subs` to `Submissions` since we don't need the space and it's a bit more intuitive.

### Old
![submission-buttons](https://f.cloud.github.com/assets/1065372/1545132/664103d4-4d71-11e3-8543-124524cb5ba1.png)

### New
![submission-buttons-new](https://f.cloud.github.com/assets/1065372/1545144/953a8ce6-4d71-11e3-9d0c-9512a75410b6.png)