Story SW-300: fixing project setup and introduction of polymorphic models

.gitattributes

...B/DBInterface/django_rest/monitoring_db/model/__init__.py

...tenanceDB/DBInterface/django_rest/monitoring_db/models.py

...ceDB/DBInterface/django_rest/monitoring_db/serializers.py

...enanceDB/DBInterface/django_rest/monitoringdb/__init__.py

...intenanceDB/DBInterface/django_rest/monitoringdb/admin.py

...aintenanceDB/DBInterface/django_rest/monitoringdb/apps.py

...Interface/django_rest/monitoringdb/migrations/__init__.py

...B/DBInterface/django_rest/monitoringdb/models/__init__.py

...BInterface/django_rest/monitoringdb/models/stationtest.py

...nceDB/DBInterface/django_rest/monitoringdb/serializers.py

...intenanceDB/DBInterface/django_rest/monitoringdb/tests.py

...intenanceDB/DBInterface/django_rest/monitoringdb/views.py

LCU/MaintenanceDB/DBInterface/django_rest/requirements.txt

LCU/MaintenanceDB/DBInterface/django_rest/settings.py