Implements blueprint bootstrap-2.
Notable changes:
* Uses new split-dropdown buttons. Fixes bug 920820 and fixes bug 918452.
* Uses bootstrap dropdowns for all menus. No differing implementations now.
* Reworks how css class attributes are consructed on actions to make them
easier to works with and support default classes.
Change-Id: Ia25edb6d8ca8a2d1ef30e8f9a36331eff4c7ae86
db1842c3d6