Add Ranking Controller node

[eborghi10]

Related to issue #86.

This PR adds a node that moves the robot (sends cmd_vel commands) based on bumper readings (bumper topic).

Instructions to execute this:

Option 1

$ roslaunch ca_gazebo create_stage_1.launch

$ rosrun ca_node ranking_controller.py

Option 2

$ roslaunch ca_gazebo create_stage_1.launch

$ rosrun ca_node smach_ranking_controller.py

$ rosrun smach_viewer smach_viewer.py

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If you want to increase the real-time update rate:

$ gz physics -u 2000

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To do list:

• The robot suddenly stops.
• Use smach for the state machine.
• Fix indentation in CMakeLists.txt.
• Install dependecies (smach, smach_ros and smach_viewer)
• Bumps are not being detected correctly with RTF > 1x.

[eborghi10]

@ernestmc I fixed the controller node. There was an issue with the bumper detection (I had to wrap an angle).

Now it's working so I'm gonna merge it!