Merge branch 'master' into selenium

.gitlab-ci.yml

.gitmodules

CODE_OF_CONDUCT.rst

CONTRIBUTING.rst

Dockerfile

aleksis/core/apps.py

aleksis/core/forms.py

aleksis/core/migrations/0001_initial.py

...s/core/migrations/0004_add_permissions_for_group_stats.py

aleksis/core/mixins.py

aleksis/core/models.py

aleksis/core/preferences.py

aleksis/core/rules.py

aleksis/core/settings.py

aleksis/core/templates/core/announcement/form.html

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

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

aleksis/core/templates/core/partials/language_form.html

aleksis/core/templates/core/person/accounts.html

aleksis/core/templates/core/person/edit.html