Add absent flag on logship macro.
Add absent flag on logship macro.

If a logship line is removed, then the corresponding configuration file
is not removed from the disk. This flag makes sure that we do remove the
files.

ministryofjustice/logstash-formula,ministryofjustice/logstash-formula,ministryofjustice/logstash-formula,ministryofjustice/logstash-formula,ministryofjustice/logstash-formula