Add accessibility accomodation request page to studio and link to said page in footer, both behind a Waffle switch. Add tests for the new page.

The LMS and edx-enterprise currently communicate via REST APIs, even
though they are all running within the same service.

Currently API URLs are constructed using LMS_ROOT_URL, but that is
problematic on some systems where the external LMS_ROOT_URL is not
accessible from the private network, or routing internal requests via
the external URL is not desireable.

This patch introduces a new setting variable LMS_INTERNAL_ROOT_URL which
defaults to the value of LMS_ROOT_URL for backwards compatibility.

The LMS and edx-enterprise will use LMS_INTERNAL_ROOT_URL to construct
API URLs instead of LMS_ROOT_URL.

  all dirs must now go into COMPREHENSIVE_THEME_DIRS.
Move comprehensive theming setup section out of startup.py and into
  settings files using new 'derived' functionality.
Add 'derive_settings' at the end of all top-level Django settings files.
Move validation of comprehensive theming settings into new apps.py
  theming file.
Split theming code into code safe to run before settings are initialized
  -and- after settings are initialized.

EDUCATOR-565 | Add POLICY_CHANGE_GRADES_ROUTING_KEY, fix errors in compute_all_grades_for_course circuitry.

move tasks into tasks.py

add more logging

This makes it possible to refer to multiple book from a single app.

This also means that Open edX branches will be able to pass bok-choy
tests (at least if the books have already been built.)

This reverts commit 65f13dde.

This reverts commit 88dd85ca, reversing
changes made to bf8aef33.

and a comment and explaining why we import aws.* in the openstack settings.

Adds a context-sensitive link to learner documentation from the LMS. The base URL defaults to Open edX learner doc and can be overridden with the base URL for edx.org learner doc.  Also relabels the tab for support from help to support.