OO-2916: Better exception handling of unavailable cover images, more validations of page from/to, utf-8 of infodoc response

OO-3102: make to print view of test statistics works with the test resource and not only within a course

OO-3055, OO-3047: implementation of taxonomy module with new site, full text search, webdav access, REST API...

OO-3087: cancel the search if timeouted, make the timeout configurable, reduce it to 15 seconds, implement it for spell checker too

OO-3087: add a timeout to the full text search requests, free the DB connection before doing the search