May improve performance.
TNL-3538

Serve branded footer JSON/HTML/CSS/JS from an API endpoint
in the branding app.  Refactor OpenEdX and EdX.org footer templates
to use the Python version of the API, ensuring that the API
values are consistent with the footer included in main.html.

Detailed changes:

* Added footer API end-point to the branding app.
* Footer API allows the language to be set with querystring parameters.
* Footer API allows showing/hiding of the OpenEdX logo using querystring parameters.
* Deprecate ENABLE_FOOTER_V3 in favor of the branding API configuration flag.
* Move no referrer script into main.html from the edx footer template.
* Rename rwd_header_footer.js to rwd_header.js
* Cache API responses.

Authors:
Awais Qureshi, Aamir Khan, Will Daly

Don't mix tabs and spaces!

<nav> element needs to include aria-label or aria-labelledby which
causes issues for the screen readers.

TNL-1510

[OPEN-444]

OPEN-307

Remove Jobs, News
Change "Vision" to "About"

Move the open edx logo inside the div

Adding a bunch of placeholder views.

indenting.

Making some styles work against LMS sass.

Adding back the old edx footer and associated icons, with a feature flag.

We need to use an Open edX footer by default (and that's what all non-edx.org
instances should base their footer off) and only use the edX footer on
edx.org.

This commit uses `SITE_NAME` to determine which footer to use.

Sites using theming or micro-sites with a `SITE_NAME` not ending in `edx.org`
should not be affected.

DOCTYPE to the top of the file.

Let staticfiles determine the footer URLs

fixes template errors

keep tos untranslated

formatting fixes

the actual urls

* Fix indentation/line break issues
* Handle marketing root URL as a separate case in marketing_link
* Move link map to its own setting.

and use it for the new marketing site links.

Update links in footer to point to the right pages.
Update link on dashboard without any classes.
Update links in header.
Update links on sign in and register pages.