Created by: fionawhim
Fixes to get IE7 in line for combo buttons and dropdowns. Also fixes some minor rendering around tab borders.
Changes the background of search in the nav to better match what rgba-capable browsers are showing against the default nav background (IE7 and IE8).
Also:
- Brings back the uneditable text input example from 1.x
- Moves the buttonBackground mixin to mixins.less (issue #1292 (closed))