RP-248 Refactoring for ros_control

Naming conventions unified with jackal and grizzly, clean up macros
Please don't make the description dependent on Gazebo. The way Jackal works in this regard is that the description is very lightweight, but the jackal_gazebo package with the actual launchers contains the dependency:

https://github.com/jackal/jackal/blob/indigo-devel/jackal_description/package.xml
https://github.com/jackal/jackal_simulator/blob/indigo-devel/jackal_gazebo/package.xml

If this scheme offends you, another way to deal with it is to xacro-in the simulation stuff separately at simulation time. See UBR-1:

https://github.com/unboundedrobotics/ubr1_preview/blob/master/ubr1_gazebo/robots/ubr1_robot.urdf.xacro

However, if we switch to this, I'd prefer to do it for all the platforms at once (ie, for Jade), rather than piecemeal.