Add stub of development doc site

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Move MenuBar JS API to a new component

Nuvola.MenuBar.setMenu call was handled in AppRunnerController
(God class antipattern).

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>