FRCSim, Gazebo v7, and GearsBot example

[DAlitz]

I fought with getting FRCSim running with Gazebo v7 for a long time and finally gave up. It appears that some of the WPI plugins are compiled against library versions that aren't compatible with Gazebo v7. I thought about trying to update the code and compile for 7; but in the end decided it was just easier to set up an Ubuntu 14.04 environment.

Along with the other code specific gotchas someone mentioned earlier, FRCSim doesn't appear to work well with Intel graphics. I'm using a Nvidia GeForce 960 graphics card.