Added blackfield on BaseHandler API
list of fields to be removed from automatic filtering
removed fields on api blackfield
Merge branch 'stable/0.2.x' of github.com:opps/opps into stable/0.2.x

* 'stable/0.2.x' of github.com:opps/opps:
  Release version 0.2.7.1
  Change calls of field "archive.url" to get_absolute_url on Image model.
  thumbor require Pillow <=2.0.0
set new version 0.2.7.2, fix opps api