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.

EDUCATOR-1335 - This Adds a dedicated app which is responsible for communication with edx-video-pipeline service. It also adds the backend for saving 3rd party transcription service credentials on edx-video-pipline and cache it in edx-val.

This also creates a new app common_initialization in order to provide a
place to run initialization code common to both the LMS and CMS.

  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.

This fixes a bug introduced in 3be0fa81

EDUCATOR-1448

Modifies paver webpack task to use production configuration in all
non-devstack environments, and a development config in devstack.

The module is still used by (at least) edx-enterprise.