Fix Cesium.js generated file.

My recent changes to generate stubs caused the fileset for Cesium.js to be created too early, meaning that shader files could get left out if they were not present on disk before the build started.

Instead of the pathconvert hackery I was using before, I fixed our custom scriptdef tasks to work with file-based ResourceCollections instead of requiring a FileSet, so that we can use the <union> directly.
Update copyright year
Merge pull request #1371 from AnalyticalGraphicsInc/fixCesiumJs

Fix Cesium.js generated file.
Merge pull request #1367 from AnalyticalGraphicsInc/fixDataSourceChanged

Raise the changed event in CzmlDataSource when CZML is loaded.
Merge remote-tracking branch 'origin/master' into balloon
Merge branch 'balloon' into dataSourceBrowser