Convert models to glTF 1.0

[pjcozzi]

The sample models in this repo are still glTF 0.8. We'll convert them to glTF 1.0 when the converter and spec are ready.

[pjcozzi]

To help users test their engine, we should probably include three glTF versions of each model:

• glTF with separate files for resources
• glTF with embedded resources
• Binary glTF

[pjcozzi]

Sample models with KHR_materials_common will be post 1.0 - #448

[pjcozzi]

@tfili there is a script here to convert all models: https://github.com/KhronosGroup/glTF/blob/master/sampleModels/convertAll.sh

I think we should put each type (collada, gltf, gltf-embedded, gltf-binary) in a separate subdirectory.

[pjcozzi]

@tfili a few sample models didn't convert/load in Cesium using the online converter:

• monster
• brainsteam
• vc

If you run into the same problem with COLLADA2GLTF, just leave the COLLADA files in the model's directory; delete the old glTF files.

[pjcozzi]

Sample models are here: https://github.com/KhronosGroup/glTF/tree/master/sampleModels

More to come.