Adjusted Sass for the doc-link so that it will work in pattern library pages and also in the edx.org theme. Added the documentation link to the edx.org theme header.

updated LMS footer to include year in copyright message

Removes most remaining hardcoded references to XSeries from the LMS. Part of ECOM-4638.

The logo in the edx.org footer now links to the edX home page, consistent with the logo in the header. ECOM-4117.

2. Add site configuration overrides to theming/helpers.py
3. Move microsite.get_value from theming/helpers to site_configuration/helpers
4. Move microsite_configuration.microsite.get_value usages to site_configuration.helpers.values

2. Update COMPREHNSIVE_THEME_DIR to COMPREHENSIVE_THEME_DIRS
3. Update paver commands to support multi theme dirs
4. Updating template loaders
5. Add ENABLE_COMPREHENSIVE_THEMING flag to enable or disable theming via settings
6. Update tests
7. Add backward compatibility for COMPREHEHNSIVE_THEME_DIR

TNL-4692

TNL-4651

This reverts commit caa5a0ac.

ECOM-4398

This was fixed on the openedx dashboard, but missed on the edx.org theme
for the dashboard.

This was fixed on the openedx dashboard, but missed on the edx.org theme
for the dashboard.

Updated dashboard UI for empty list of courses and programs