CORE-4993 Removed TreeStore#removeChildren KLUDGE.

GXT 3.0.6 fixed the bug in TreeStore#removeChildren and now removes the children from their parent TreeModel wrapper as well.
CORE-5001 Subtract filtered items from selection total.

Updated FolderContentsRpcProxy to set the total_filtered count from the results in the Folder whose contents was loaded.
Updated DiskResourceViewImpl to subtract the total_filtered count from the selection count that is set in the SelectionModel.
Merge branch 'master' into STABLE