OO-2541, OO-2536: optimize resolve method of merge source for the standard case, add virtual "finished" folder for finished courses, lazy load quota for the course container

OO-1069: round of optimizations, escape the & character, async reload the list of courses, groups and shared folders...

OO-1004: encode softly the webdav names for group and resources to preserve as much as characters as possible

OO-1004: encode softly the webdav names for group and resources to preserve as much as characters as possible

OO-470: merged containers are transient with an init method to initialize them after deserialization

OO-291:  enhance the main search function for groups, add search in waiting list, add search of public group, add unit tests

OO-291: first step: move business gourp manager to a business group service, remove dependency to the context...

OO-157: optimization of WebDAV, reduce the number of DB queries with lazy loading, specific resolve method, lazy loading of quota...