Curiosity path model missing plugins and assets

[dirksavage88]

The current curiosity path used in the demo is a blank terrain canvas. There is particle support in gazebo (good for simulating martian weather) and existing assets could added for future moon to mars mission testing (cargo transport being one mission for an autonomous rover)

A fix would include the particle emitter plugin and also add existing moon/mars relevant assets.

[dirksavage88]

One issue I've run into is that ignition tends to ignore the *.obj files and will only open *.dae files