Added setting to enable/disable library indexing + moved is_index_enabled into search indexer classes
Added task and signal to fire library reindex

- sharing enabled for custom URLs only if URL actually specified

Indexing moved to celery task. Reorganised indexing to always allow for full course reindex. Indexing code no longer needs to be in common, because it is triggered by signal instead of being called.g

The replacement strings need to be unicode, so that when STUDIO_NAME contains non-ascii characters python can handle it correctly without raising exceptions.
Also, the value of STUDIO_SHORT_NAME can be read from cms.env.json.

This makes these files importable, and puts them into the new best guess
as to where files should live.

When configured, set an additional cookie with the CSRF
token for use by subdomains.

The cookie can have a different name than the default
CSRF cookie, preventing conflicts between cookies
from different domains (e.g. ".edx.org", "courses.edx.org",
and "edge.edx.org").

The new cookie is included only on the enrollment API
views so that the scope of this change is limited
to the end-points that require cross-domain POST requests.

This allows the holder of a third-party access token (e.g. from Google
or Facebook) to get a first-party access token for the edX account
linked to the given access token.

When configured, set an additional cookie with the CSRF
token for use by subdomains.

The cookie can have a different name than the default
CSRF cookie, preventing conflicts between cookies
from different domains (e.g. ".edx.org", "courses.edx.org",
and "edge.edx.org").

The new cookie is included only on the enrollment API
views so that the scope of this change is limited
to the end-points that require cross-domain POST requests.

This is compatible with Django > 1.5, and allows us to re-enable the ProfilingDebugPanel

The new "country access" implementation replaces the old
implementation.  Middleware and tests have been updated
accordingly, but deprecated models are preserved
for backwards compatibility.

xblock-external-ui: Alternate referer check for CORS requests
xblock-external-ui: Allow to disable httponly on session cookies
xblock-external-ui: Add a unit test for CorsCSRFMiddleware

TNL-1380

This reverts commit b8184d18.

[second attempt which addresses bug building Studio]

This reverts commit 1d6fceda.

Respond to review comments:

- Rename build and config files for consistency between lms/studio.
- Fix merge conflicts with lms require config.
- Devstack uses optimized pipeline to skip require JS optimizer step
- Add tests for render_require_js_path_overrides

path.py objects report themselves as class objects, which confuses the heck out of
pylint. It tries to match variable names using the class-rgx regular expression
instead of the constant-rgx regular expression, and it doesn't match, so it
throws an error. Not sure how to fix pylint, so we'll just ignore these errors.

TNL-652

Co-Authored-By: Jean-Michel Claus <jmc@edx.org>
Co-Authored-By: Brian Talbot <btalbot@edx.org>
Co-Authored-By: Tim Babych <tim@edx.org>
Co-Authored-By: Oleg Marshev <oleg@edx.org>
Co-Authored-By: Chris Rodriguez <crodriguez@edx.org>

SOL-1, SOL-2, SOL-3