Renaming and reorganizing namespaces

Making the code more organized and splitting a couple of objects
down to make things clearer.
[Broken] Adding SliderTool
[WIP] Refactoring the way the toolbar is initialized

Trying to figure out the best way to initialize toolbar buttons
from OOUI.
Refactoring OOUI toolbar

Borrowing heavily from VisualEditor's way of constructing the toolbar
since OOJS was built with VE in mind. Reorganizing the toolbar to work
with tool objects and listen to scenario states.