Adjusts cancel button margin

Ensures it's vertically centered

**Before:**

![screenshot 2014-10-09 22 07 02](https://cloud.githubusercontent.com/assets/65052/4588154/e199dbf0-503b-11e4-9579-aff664b04111.png)

**After:**

![screenshot 2014-10-09 22 06 49](https://cloud.githubusercontent.com/assets/65052/4588155/e44d561a-503b-11e4-87f5-fa58ad956a4d.png)