px4_solution

1st solution
cd ~/git/simulation/ros_packages/px4_firmware
git checkout v1.11.1
cd
cd ~/mrs_workspace
catkin clean
catkin build

2nd solution
cd ~/git/uav_core
gitman install -f
cd ~/git/simulation
gitman install -f
cd ~/git/uav_core/installation
./install.sh
cd ~/mrs_workspace
catkin build