Remove sample coverage to keep in sync with glTF 0.8
Update model tests for glTF 0.8 update
Async picking of rasterized features in imagery layers.

For example, by using the WMS GetFeatureInfo service.
Show position of selected feature.
If feature position is not known, use pick location.
Merge remote-tracking branch 'origin/master' into imageryLayerPicking
Add support for MapInfo GetFeatureInfo.
Add support for Esri WMS servers.
Add support for unknown GetFeatureInfo responses.
Give user control over GetFeatureInfo format.

Also add specs WebMapServiceImageryProvider.pickFeatures.
Add pickFeatures as an optional function on ImageryProvider.
Simplify layer feature picking and improve doc.
Matrix4 - Fix many sample code problems.
Occluder - fixes for sample code.
pickImageryLayerFeatures specs, and fix typo.
Add specs for Globe.pickImageryLayerFeatures.
Merge remote-tracking branch 'origin/master' into gltf-8-tweaks
Handle ServiceExceptions by reporting "No Features".
Update CHANGES.md.
Fix jshint warning.