added created_by_da field to PerformanceData and set null=True for it and created_by
did schemamigration for model change
updated test utils to create DistrictUserAdmin
added related key to teacher performance data
wrote unittest for teacher performance data
updated tests for teacherperfomance created to account for created by district admin
added created_by_da to api and set created_by to null
wrote unittest for learner perfomance data
removed test_migrations that were causing failures
fixed failure caused by using postgres instead of sqlite as test_db
Merge branch 'develop' into feature/issue-91-add-district-admin-USSD-reporting-functionality
Merge branch 'develop' into feature/issue-91-add-district-admin-USSD-reporting-functionality
Merge branch 'feature/issue-91-add-district-admin-USSD-reporting-functionality' into develop