Changes for compatibility with latest python-social-auth (0.2.7)

common/djangoapps/auth_exchange/forms.py

common/djangoapps/auth_exchange/tests/test_forms.py

common/djangoapps/student/views.py

common/djangoapps/third_party_auth/pipeline.py

common/djangoapps/third_party_auth/provider.py

common/djangoapps/third_party_auth/tests/specs/base.py

...angoapps/third_party_auth/tests/test_change_enrollment.py

common/djangoapps/third_party_auth/tests/utils.py

common/test/db_cache/bok_choy_schema.sql

common/test/db_cache/lettuce.db

lms/envs/test.py

requirements/edx/base.txt