Joystick update

I've found out why I couldn't choose position or force control: they were missing the bits added lastly on the mavlink setpoint messages (reported [here](https://github.com/PX4/Firmware/issues/1288#issuecomment-53581938)).
Also, I merged the last `master` commits.

If I now want to add the velocity control, what should be done? (sorry to insist on this but I really need velocity setpoint control to work :S)
Thanks!