Stereo layers persist in HMD after VR Preview

Stereo layers persist in the HMD after VR Preview is closed.  This persists through opening other maps and using VR Preview in those maps. 

 Note: 4298992 in //UE4/Main is the CL just before //UE4/Dev-VR's copy-up.

1. Sync and Compile QAGame project
2. Open QAGame project in editor
3. Open TM-StereoLayers
4. Click the dropdown next to Play and select VR Preview
5. In the HMD note the face locked and world locked stereo layers appear
6. Close VR Preview while HMD is still on

Expected Results: Stereo Layers are removed with the rest of the map when VR Preview is closed

Observed Results: Stereo Layers persist in the HMD even after VR Preview is closed.