start moving AT-related parts of the default profile here
moved from CMFPlone
Merge remote-tracking branch 'origin/master' into davisagli-optional-archetypes
re-remove references to archetypes.kss
Merge branch 'davisagli-optional-archetypes'
 merge PLIP 12344 - optional archetypes and integrate plone.app.event:

- Depend on and install plone.app.event and remove all Event related code.
  There is still the IATEvent interface and the ATEvent content type class, but
  latter inherits from plone.app.event.at.content.ATEvent, making external code
  forwards compatible with plone.app.event. (Merge of PLIP 10886)
  [thet et al.]

- Move content type profile definitions from Products.CMFPlone into here.
  (Merge of PLIP 12344)
  [davisagli et al.]