Update README.md to b26
Add missing files
Updated to Cesium master (b28+)
Merge branch 'master' into viewer

Conflicts:
	ThirdParty/Cesium/Widgets/InfoBox/InfoBox.css
	ThirdParty/Cesium/Workers/createVerticesFromQuantizedTerrainMesh.js
	ThirdParty/Cesium/Workers/sanitizeHtml.js
	ThirdParty/Cesium/Workers/upsampleQuantizedTerrainMesh.js