Release 6.20.0: New Spanish name for Spam folder

[changerequest]

In the file User.properties in directory /opt/open-xchange/etc/admindaemon the following property

SPAM_MAILFOLDER_ES_ES=Correo basura

is changed to

SPAM_MAILFOLDER_ES_ES=Correo no deseado

This seems to be a better Spanish name for the Spam folder.