get_containerbox_list adding template tag, returns a list of sublists of containers a containerbox
edit template articlebox_container_list.html
Merge branch 'master' of https://github.com/heltonalves99/opps

* 'master' of https://github.com/heltonalves99/opps:
  edit template articlebox_container_list.html
  get_containerbox_list adding template tag, returns a list of sublists of containers a containerbox
Fix pep8, merge #257