* Move all core functions from mains.js to background.js
* Use message interface for IPCs between main.js, background.js and popup.js
* Add popup interface :
* safest method to compute masterkey
* Direct access to our own gPass server with auto URL and username fill
* Add some specific menus :
* Access to gPass settings
* Allow to disable extension
* Update gPass icon when a password field has focus and gPass is ready to work
