Faceshift starts reporting failure to track under load, so determine active
state based on the amount of time elapsed since last successful tracking data
received.
Merge pull request #979 from ey6es/master

Faceshift starts reporting failure to track under load, so determine act...
Merge branch 'master' of https://github.com/worklist/hifi into blendface
Use shaders for eyes (like the ones for the iris).