Remove TiltBrushExamples from the .unitypackage
Remove TiltBrushExamples from the .unitypackage

- It no longer compiles with current versions of SteamVR
- Makes users think that TBT requires SteamVR, which it doesn't
- Tilt Brush Toollkit is not an appropriate place for educational
  materials on creating VR apps in Unity with SteamVR

Change-Id: Id000b01505e0e08b764bd64b3b228f84f5b142f5

googlevr/tilt-brush-toolkit,googlevr/tilt-brush-toolkit