Implement dropdown that: 
* open on click for top menus
* open on hover for sub-menus
* close on action click on any menu element.

Made htmlkickstart classes declarative in menu.html no more set from
menu.js.

Introduced ui.bootstrap 'open' class from menu.js 

There seems to be an synchronisation issue with the DOM state for
onhoveropen HTML class set in the view while the model is built 
from the controller and modified based upon onhoveropen class presence
or absence (might need fix by setting 'onhoveropen' at backend).