OO-3489, OO-3490, OO-3491, OO-3495, OO-3499, OO-3500, OO-3501: finish the export process, delete files after zipping, send email... and more exported data

OO-3489, OO-3492, OO-3493, OO-3494, OO-3496, OO-3497: infrastructure to export user data, export  portraits, notes, personal folder, calendars, subscriptions, delete calendars after usser deletion