createlinks: restart sogod in nethserver-sogo-update event. Refs #1843
sogo-config template: use 127.0.0.1:587 as smtp server. Refs #1817
sogo-config template: add ldap group source. Refs #1842
createlinks, nethserver-sogo-backup-user: add nethserver-sogo-backup-user to pre-backup-data event. Refs #1800