Rewrite frontend as fullscreen apps

The desktop metaphor is getting hard to maintain:

• All user actions are on the same page/url as far as the browser is concerned, which put the burden on the developer to avoid memory leaks (HUE-585).
• JS goes through layers of wrappers, which makes frontend debugging hard.
• We have to maintain the jframe layer, track MooTools versions and incompatibilities, and fix bugs on different browsers.

The proposal is to drop the desktop metaphore and make each app fullscreen. The dock becomes the app toolbar. Apps (and links to views) are full page loads with different URLs, which are easily linkable. The ability to open things in new browser tabs compensates for the loss of jframe. Certain interactions can still be done over AJAX, as dictated by the desired user experience.

This will break compatibility of SDK apps. The decorative HTML (i.e. "behaviours" data filters) will not work. We should establish a pattern for app transition and make it as easy as possible.