correctly

Fix a bug in GLTF cache

 Fix buggy check in setPositionOnNavMesh

Create only necessary A-Frame entities for GLTF models

If we know ahead of time which entities will have components on
them or a template attached to them, then we can identify scene
graph subtrees which can act as leaves of the entity tree and
refrain from inflating extra entities underneath them.

Just doing this to try to get buildbot to spit out a build with new code for #422

Media sharing tools

Merge branch 'feature/image-interactables' of https://github.com/mozilla/hubs into feature/image-interactables

since it interferes with pasting

Merge branch 'feature/image-interactables' of https://github.com/mozilla/hubs into feature/image-interactables

caching for gifs

Add the ability to spawn 3D models