Adds tests for PendulumViewController and PendulumBehaviour

Also corrects a logic error in # dragWeight which allowed the box to be
dragged from anywhere in the view vs just from within the box itself.

Changes some  some non-objective-c method names from camel case to
snake case.

Adds @help_methods.window_cleanup(window, controller) to all but one
spec test file.

Renames ivar @view to @decoration_view in DecorationView class.