Add celery task for MySQL import script

aleksis/apps/untis/tasks.py

+from aleksis.core.util.core_helpers import celery_optional
+
+from .util.mysql.main import untis_import_mysql as _untis_import_mysql
+
+
+@celery_optional
+def untis_import_mysql():
+    """ Celery task for import of UNTIS data from MySQL """
+    _untis_import_mysql()