Generate Polyline and valid fix in gazebo

[chsahit]

We need a way to mock what google maps does in the real world for gazebo

[irapha]

Ideally, we'd need an easy way (maybe a tool?) to define a polyline inside gazebo (where you can see the world) and then it'll spit out that polyline and we can put it in each individual test case as a publish('/polyline', polyline)