Resolve "clean initial database"

Closes #345 (closed)

This PRC implements following changes:

1. nd_number field is renamed to Subject number (ND is for NCER)
2. following fields will be removed in new installations of smasch: mpower_id, screening, diagnosis, previously_in_study, year_of_diagnosis, pd_in_family, brain_donation_agreement, virus_test_X, virus_test_X_updated, virus_test_X_collection_date, virus_test_X_iga_status, virus_test_X_igg_status. In the existing studies (wiuth at least one subject) the fields would have to removed manually
3. I added a gitlab CI test to check if create_dummy_data script runs without errors