Controlpanel configlet

@hammertoe main changes:

  - Should no longer pull in plone.app.contenttypes upon adding package to your buildout, unless the test or benchmark extras are requested.

  - The shadowtree requires building upon installation, this can be done manually by visiting the control panel and selecting the experimental security indexing configlet (no paging of paths currently, but should limit the number of results shown to 10)

 - The shadowtree is now stored and accessed via a tool 'portal_shadowtree' (which is also the context for control panel configlet)

 - The main algorithm uses itertools.groupby instead of building an OrderedDict to group shadowtree nodes. 
  
 - Subscribers now handle the manipulation of shadowtree nodes when temporary objects get created  when adding an item TTW

 - Added functional tests for the control panel tool, increased number of tests

 - Unified buildout to a single configuration (+1 for travis)