Merge branch 'master' into 40-link-data-to-school-term

aleksis/core/apps.py

aleksis/core/mixins.py

aleksis/core/models.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

aleksis/core/templates/core/group_type/list.html

aleksis/core/templates/core/index.html

aleksis/core/templates/core/management/data_management.html

aleksis/core/templates/core/pages/about.html