The quadcopter_navigation package can be found here
In Terminal 1
#Runs the Gazebo world
roslaunch quadcopter_gazebo quadcopter.launch
In Terminal 2
# Runs the code for hovering the drone
roslaunch quadcopter_takeoff_land quadcopter_takeoff_land.launch
In Terminal 3
Runs the rviz visualization tool and allows 2D nav goal for navigation in Rviz
roslaunch quadcopter_navigation quadcopter_move_base.launch
In Terminal 4
Lands the drone
rostopic pub /quadcopter_land -r 5 std_msgs/Empty "{}"