Fixed bug (missing tf2-geometry) in Dockerfile and added setup.bash sourcing

[samlaf]

The dockerfile was missing apt-get install ros-melodic/kinetic-tf2-geometry-msgs.
I was getting this error

Errors << orb_slam2_ros:make /home/logs/orb_slam2_ros/build.make.000.log       
In file included from /home/src/orb_slam_2_ros/ros/src/Node.cc:1:0:
/home/src/orb_slam_2_ros/ros/include/Node.h:34:49: fatal error: tf2_geometry_msgs/tf2_geometry_msgs.h: No such file or directory
compilation terminated.
make[2]: *** [CMakeFiles/orb_slam2_ros_mono.dir/ros/src/Node.cc.o] Error 1
make[2]: *** Waiting for unfinished jobs....
In file included from /home/src/orb_slam_2_ros/ros/include/MonoNode.h:37:0,
                 from /home/src/orb_slam_2_ros/ros/src/MonoNode.cc:1:
/home/src/orb_slam_2_ros/ros/include/Node.h:34:49: fatal error: tf2_geometry_msgs/tf2_geometry_msgs.h: No such file or directory
compilation terminated.

I also added sourcing devel/setup.bash and bash as the default command so that it sources .bashrc (and hence devel/setup.bash), so that we can roslaunch orb_slam_2_ros right after running the Docker container.