Make RC and Camara Screen usable in portrait mode

Because my changes in issue #147 brakes the forced portrait mode for the rc and camera view and because I'm thinking about expanding the split screen functionality, I made the both views working in all screen orientations.

(I replaced the DualJoystickView by two JoystickViews and extend the JoystickView a little bit to make it easier to modify the layout just by changing the layout.xml file)