Release notes: * https://www.elastic.co/guide/en/elasticsearch/reference/5.5/release-notes-5.5.2.html * https://www.elastic.co/guide/en/logstash/5.5/logstash-5-5-2.html * https://www.elastic.co/guide/en/kibana/current/release-notes-5.5.2.html
* Add kibana5 and logstash5 * Upgrade the elastic beats to 5.4 * Make sure all elastic products use the same version (see elk5Version) * Add a test for the ELK stack