Disabled deprecated autocreate dovecot plugin

 * Using mailbox and namespaces instead
Update changelog
Merge branch 'master' into mjulian/dovecot-autocreate-deprecated

Conflicts:
	main/mail/ChangeLog
Merge pull request #1319 from Zentyal/mjulian/dovecot-autocreate-deprecated

Mjulian/dovecot autocreate deprecated