ldap: More detailed exception text in case of connection errors
FIX: Fixed rendering bug after folder editing
(The references from parent to child folders are updated during load_folders now)
FIX: mssql_backup: Fixed wrong calculation of backup age in seconds
FIX: mssql_backup: Fixed wrong calculation of backup age in seconds (now python <2.7 supported)
Allowing "%" and "+" in mail prefixes of contacts now