Added OverlayRenderer class and moved displayOverlay from Application to
OverlayRenderer.
Merge branch 'master' of https://github.com/highfidelity/hifi
Made Overlay appear as flat image in front of camera in Oculus Rift. It
needs to be a curved surface instead.
Merge branch 'master' of https://github.com/highfidelity/hifi

Conflicts:
	interface/src/Application.cpp
	interface/src/Application.h
Touched up comments
Fixed coding standard issues
Merge branch 'master' of https://github.com/highfidelity/hifi
Fixed SkeletonModel compilation errors with PrioVR
Renamed OverlayRenderer to ApplicationOverlay and moved it up a directory
Merge pull request #2934 from Barnold1953/master

OverlayRenderer class and display Overlays to Oculus