Fix pylint violations (mostly removing pylint pragmas)

lti_consumer/lti_1p1/consumer.py

lti_consumer/lti_1p1/oauth.py

lti_consumer/lti_1p3/exceptions.py

lti_consumer/lti_xblock.py

lti_consumer/outcomes.py

lti_consumer/plugin/views.py

lti_consumer/tests/unit/test_lti_xblock.py

lti_consumer/tests/unit/test_models.py

lti_consumer/utils.py

setup.cfg