Route validation improvements

Ideas to make route validation more "secure" :

• Add a button on route to send for validation
• When route author clicks it, it sends a notification to the routeManagers members saying there is a route to validate.
  The access rights on the route could be modified automatically : routeManagers are granted write (or manage everything), and lock route so no modification can be done.
• routeManagers can then validate.
  -> Route change lifecycle state to "validated".