Flight not really stable enough.

Merge branch 'mothership' into valentin

-Added DroneX yaml button to load parameters from yaml files.
-Added DroneX states: ground, take_off, hover, approach, land on mothership,
land on ground, on mothership
-Added onButtonPressed functions
-Deadlocks in onTakeOff, onLandOnMothership, OnAbort in DroneXControllerService
possible

Added necessary files for DroneX Controller

Picker controller working nicely (on laptop 4) and code commented with simple explanation of what to do

Added squat functions to picker and connected to GUI button. Also added parameters for object thickness at pickup and put down locations

Added files for Picker node and integrated into student GUI, PPSClient, and Paramter service, needs testing

Added new tabs to the flying agent GUI as separate classes. The classes still need to be implemented