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

OO-1075: force the group by for all databases but MySQL (it's the only DB where the group by is case insensitive)

OO-716: fix multiple choice stats in survey, there is no wrong answer there but the QTI return 1 point for the first response and 0 for the next, remove the empty responses from the stats of essay

OO-1083: check if the 2 objects are of the same class before compare them with the generic compareTo method

OO-1016: better debugging of e-mails, don't send user info to factory for drop box subscription's context