used mptt
used mptt on admin
change treebeard to mptt
channel form admin, set slug to readonly
generate initial migratin
Merge branch 'master' of github.com:opps/opps

* 'master' of github.com:opps/opps:
  Update CHANGELOG
  Update CHANGELOG
  Add OPPS_CORE_APPS, thanks to Django 1.7
  Improves python 3 compatibility
  Fix initial migration for Channels
  Change long_slug column verbose name
  Fixes __future__ import position
  Replaces unicode for python 3 compatibility

Conflicts:
	opps/channels/migrations/0001_initial.py
	opps/channels/models.py
update migrate initial channel