ROS2 change of param types, backporting the use of dynamic reconfigure

[BrettRD]

I'm documenting the parameters used by the various aspects of Fuse, some of them can't be migrated to ros2 because ROS2 has stricter type checking

Specifically, optimiser/motion_models and optimiser/sensor_models use XmlRpc::XmlRpcValue::TypeArray which doesn't exist in ROS2.
In the ROS2 branch, I need to change the yaml structure to declare the names of the motion_models and sensor_models first, then fill in the properties of each afterwards.

examples of a proposed ROS2 compatible format: fuse_simple_tutorial range_sensor_tutorial

ROS2 also encourages the use of a built-in callback that is triggered when parameters change. In ROS1, this was handled by dynamic_reconfigure.
It seems like dynamic_reconfigure would be useful, should I make the effort to streamline a back-port?

[methylDragon]

With the completion of #276 , a way to list parameter names has been devised (and pending upstream)

So we can now preserve the structure of the yamls!

That said, dynamic_reconfigure-like behavior would be good to include.

[Ryanf55]

If you need help with dynamic reconfigure, let me know. For the aerial drones, there are a few places we could make use of dynamic reconfiguration for the constrains in the model.