Merge branch 'master' into 265-dropdown-for-languages

aleksis/core/apps.py

aleksis/core/forms.py

aleksis/core/menus.py

aleksis/core/mixins.py

aleksis/core/models.py

aleksis/core/rules.py

aleksis/core/tables.py

aleksis/core/templates/403.html

aleksis/core/templates/404.html

aleksis/core/templates/500.html

aleksis/core/templates/503.html

aleksis/core/templates/core/additional_field/edit.html

aleksis/core/templates/core/additional_field/list.html

aleksis/core/templates/core/base.html

aleksis/core/templates/core/base_print.html

aleksis/core/templates/core/group/child_groups.html

aleksis/core/templates/core/group/edit.html

aleksis/core/templates/core/group/full.html

aleksis/core/templates/core/group/list.html

aleksis/core/templates/core/group_type/edit.html