leap vm add should tag the new vm with all node tags

To prevent a huge bill from leftover, long-running VMs used for CI, I created a aws lambda function to kill those which are older than a day.

In order to terminate all only old leftover CI instances, we need to have them tagged as "ci", so we don't kill other instances.

(from redmine: created on 2016-09-08, closed on 2016-09-09, relates #8450 (closed))