Release 6.20.0: Add configuration property to specify a Ham bounce address for the Cloudmark spamhandler.

[changerequest]

Added the following property to spamhandler_cloudmark.properties:

# Defines the eMail address to which the selected eMails will be bounced if they
# are marked as Ham. If no address is specified the bounce will be skipped,
# but moving the selected mails back to the Inbox will still be processed.
com.openexchange.spamhandler.cloudmark.targetHamEm ailAddress=