Iconic integration with components

Some components will automatically color Iconic icons inside of them, based on how mixins are used or the coloring class of the parent.

**Components:**
 - [x] Button
 - [x] Button group
 - [x] Menu bar
 - [ ] Notification
 - [x] Title bar

Notifications are weird because the directive is hardcoded to just take a `src` attribute of an image and stick it in there, which means it can't compile a `zf-iconic` directive in the process. We'll have to look into that.