Bug 1042960 - Create UI elements for facet bar

This is a WIP that addresses two challenges with the design for bug 1042960.

1) One-sided borders are tough. They require hacky layer lists or a 9 patch, which is doable, except:
2) How would we change their colors based on the search engine? 
Yes, I just meant that we wouldn't want the pressed and selected styles to be the same thing. Like, we would want a new style for pressed.