Admin features

Added following functions to the pb.AdminNavigation

    pb.AdminNavigation.add(node)
    pb.AdminNavigation.addChild(parentId, node)

addChild can be called at any time even before the parent tree node exists, this is just in case someone will ever need to do something like this. The navigation will only be built once on startup so the overhead should be really low.

i also added an adminSample Plugin to show off the admin related features.
Hm yeah that would probably be a really good idea so users potentially change change the Language independant of the dystem language. i'll try to figure out a way to make this happen. I dont think it will be ready today but i think you will see a new commit tomorrow ;-)