Support for remaining DO_JUMP repetitions

With this change a waypoint message of a DO_JUMP waypoint is accepted even if not requested. It is a workaround in order to allow QGC to show how many repetitions are left.

According to the [mavlink waypoint protocol](http://qgroundcontrol.org/mavlink/waypoint_protocol#waypoint_protocol) there is no straightforward way on how to do this.

This needs [changes on the firmware side](https://github.com/PX4/Firmware/pull/1518) as well.