use star shaped check buttons to select mounts

I've had this for awhile and thought I would share! Visually, I like it a lot more than just check boxes. It just uses the star button textures Blizzard added for bonus reps.

![wowscrnshot_112213_055957](https://f.cloud.github.com/assets/1010803/1600432/a44a067c-536f-11e3-8fd4-982f10e79c6d.jpg)

nebula169 on #wowace :p