Improve footer toolbars in dialogs

@devoncarew

* Hide footer toolbars when there are no items or no visible items
* Increase spacing between buttons (was 0)

![screen shot 2014-06-13 at 7 03 22 am](https://cloud.githubusercontent.com/assets/5606182/3270781/e3115aac-f303-11e3-8bf6-6bb8039c9418.png)
===>
![screen shot 2014-06-13 at 7 05 47 am](https://cloud.githubusercontent.com/assets/5606182/3270782/ea5a6eca-f303-11e3-9e3b-3e2361e60589.png)

![screen shot 2014-06-13 at 7 03 34 am](https://cloud.githubusercontent.com/assets/5606182/3270802/0d7d0110-f304-11e3-8fe6-b1b0fdd9eb59.png)
===>
![screen shot 2014-06-13 at 7 06 00 am](https://cloud.githubusercontent.com/assets/5606182/3270806/145844e0-f304-11e3-9eb5-1f67ed56d01c.png)