Cnx-archive

-----

- Correct canonical URL (remove versions)

-----

- add test for canonical link to HTTP header of PDF download urls

-----

- add canonical link to HTTP header of PDF download urls

-----

- Remove sort from search filter list (586)

-----

- Set Cache-Control headers in archive (580)
- search speed ups, using fulltext - supports all the filters in advanced search
- Contextual page extras check that the page is in the book (577)
- Build sitemap without stripping special chars to match Webview url (556)
- Faster book extras and more accurate contextual page extras (575)
- Update README, install docker, correct test config file

-----

- Documentation for OAI Feed
- Fix failing tests due to get_extra changes
- Allow short ids for the page extras
- Allow contextual urls in the page extras