Whitespace.
Remove study_center reference from staff model.
Remove PSU reference from outreach_event and system_configuration. #3470.
Update navigator_configuration to use branch 'issues_16_17' which has optional sc_id and sampling_units_file. #3470.
Fix syntax. #3470.
Update ncs_navigator_configuration to user branch 'issues_16_17_18'.
Update ncs_naviagtor_configuration to refer branch 'non_required_fields'.
Use ncs_navigator_configuration 0.4.0 version. #3470.
Remove study center from enumerator. #3470.
Merge pull request #4 from NUBIC/feature_3470

Make Ops Study center and PSU independent. #3470