Make button sizes consistent

On the backend control panel, the button sizes for the CHANGELOG, Donate, and Reload actions are inconsistent between Core and Pro as well as the different buttons.  This makes everything consistent with `btn-small` (which is in place on the Reload button already).

![screen shot 2014-08-20 at 11 11 40 am](https://cloud.githubusercontent.com/assets/368545/3983089/b7bec408-287c-11e4-89a1-d6d4fd359945.png)
![screen shot 2014-08-20 at 11 11 52 am](https://cloud.githubusercontent.com/assets/368545/3983090/b8c495f8-287c-11e4-91df-9ff33adc0a54.png)