group-create event cleanup: removed nethserver-mail-default-pseudonyms-create action. Refs #1795
nethserver-mail-group-acl-adjust action: don't die() but go on if a group setting fails..
/etc/dovecot/dovecot.conf template (20users,40namespaces): refactored settings. Refs #1879
/etc/dovecot/dovecot.conf (50shared_groups): declare shared group namespaces disabled. Shared groups are selectively enabled by dovecot-postlogin script. Refs #1879
/etc/dovecot/dovecot.conf (40namespaces): mail_shared_explicit_inbox, shared INBOX be visible as "shared/user" or "shared/user/INBOX". Refs #1879
/etc/dovecot/dovecot.conf (40namespaces): configure IMAP SPECIAL-USE extension. Refs #1879
/etc/dovecot/dovecot.conf (40namespaces): enabled Listescape plugin. Refs #2003