Add CPC sensor model to simulated vehicle

To measure the particle concentration using the algorithm described in Tian, 2010, the vehicle must have a sensor unit from the chemical particle concentration available in the uuv_sensor_ros_plugins. A number of URDF snippets to initialize this sensor in the URDF robot description can be found in the sensor package. One example of implementation is already presented in the description of the rexrov2 vehicle in the declaration of its sensor units as shown below

<!-- Mount chemical particle concentration sensor -->
  <origin xyz="0 0 0" rpy="0 0 0"/>

A sample of the output in rviz and rqt can be seen below. Feel free to check the sample plume script and the URDF sensor snippets to see the input arguments that can be changed to modify both the plume and concentration sensor settings.


Plume RViz

Plume RViz Sensor