TMSS-190: merged master into this feature branch

Docker/lofar-ci/Dockerfile_ci_sas

SAS/TMSS/docker-compose-ua.yml

SAS/TMSS/src/tmss/settings.py

SAS/TMSS/src/tmss/tmssapp/models/scheduling.py

SAS/TMSS/src/tmss/tmssapp/models/specification.py

SAS/TMSS/src/tmss/tmssapp/populate.py

...chemas/scheduling_constraints_template-constraints-1.json

SAS/TMSS/src/tmss/tmssapp/serializers/specification.py

SAS/TMSS/src/tmss/tmssapp/viewsets/scheduling.py

SAS/TMSS/src/tmss/tmssapp/viewsets/specification.py

SAS/TMSS/src/tmss/urls.py

SAS/TMSS/test/test_utils.py