The upgrade to Django 2.2 has caused a spike in production logging due to RemovedInDjango30Warning deprecation warnings. For now, turn off logging of DeprecationWarning, ImportWarning, and PendingDeprecationWarning whenever we're using WSGI (they'll continue to be logged in devstack). We may eventually want this behind an easily flipped toggle, but for now just remove it to get this resolved quickly.

This will remove imports from __future__ that are no longer needed.

https://docs.python.org/3.5/library/2to3.html#2to3fixer-future

Highlights:
* The url '/shib-login/' interfaces with apache/mod_shib via
  request.META to handle shibboleth login and registrations
* Courses can designate 'enrollment_domains' to limit enrollment
  to users with a linked ExternalAuthMap verified by a particular
  identity provider
* Tests
* Logging

 Changes to be committed:

	new file:   common/djangoapps/external_auth/migrations/0001_initial.py
	new file:   common/djangoapps/external_auth/migrations/__init__.py
	new file:   common/djangoapps/external_auth/tests/test_shib.py
	modified:   common/djangoapps/external_auth/views.py
	modified:   common/djangoapps/student/views.py
	modified:   common/lib/xmodule/xmodule/course_module.py
	modified:   lms/djangoapps/courseware/access.py
	modified:   lms/djangoapps/courseware/tests/test_access.py
	modified:   lms/envs/common.py
	modified:   lms/envs/dev.py
	modified:   lms/envs/test.py
	modified:   lms/templates/courseware/course_about.html
	modified:   lms/templates/dashboard.html
	modified:   lms/templates/extauth_failure.html
	modified:   lms/templates/navigation.html
	modified:   lms/templates/register.html
	modified:   lms/templates/signup_modal.html
	modified:   lms/urls.py
	renamed:    lms/wsgi_apache.py -> lms/wsgi_apache_lms.py

wsgi_apache.py passes an apache env variable for SERVICE_VARIANT
to the os environment, where it's normally set when we use gunicorn