Add descriptors for wide-area tracking systems with built-in VRPN servers

[rpavlik]

Both OptiTrack Motive (for a long time) and (at least recently) Vicon include built-in VRPN servers in their wide-area tracking systems, and so they are very easily/readily compatible with OSVR: they just need descriptors written.

Write basic/generic descriptors so that the Compatibility Aggregator picks these systems up and lists them on the compatibility page on the web site.

cc @VRguy