Added busy indicator to metadata editor.

Change-Id: Ice6d89265d8049a8b89ee6fa5d856986cb9946be
Added CustomTree.enableDoubleClickToExpand() and used it in
MetadataManager.
Improved behavior of WeaveTree context menu items.

Change-Id: Ic0f638eecdb12a2f66926ea71ff38b4607d6abee