[BUGFIX] Controllers must not be of scope singleton
Removes the scope("singleton") annotation from the
provided base controllers.
Usually the scope of a controller doesn't really make a difference,
because they are only instantiated once per request.
But if the same controller is used multiple times
(e.g. within two plugin/widget instances on one page) the side
effects could be very confusing.
Releases: master, 2.0