Menu - Adds support for Experimental UI section which includes the
new navigation structure in it's current state.

This commit does not reflect the final state of the menu, as there
are current and potential future usability issues to address. What's
included:
 - ability to turn experimental UI on and off per user
 - new navigation structure in experimental mode
 - modified navigation rendering for experimentation
 - tests for new navigation rendering
Setting the active menu tab based on location.
Adding some comments to the menu controller.
Allowing logout via get as it is an action and not a resource.
Adding notification menu item to active menu item check.
Making notification count update when a notice is generated.