WIP.
progress:
 - Fixed shadowtree.Node path caculation/manipulation (did not match 'real world')
 - Made shadowtree.Node.ensure_ancestry_to an instance method now we have a get_root factory.
 - Got tests passing for shadow tree integrity (Added subscribers for ObjectAdded/ObjectRemoved events for IContentish objects)
 - Added boilerplate for GS uninstall profile and TODO.