Comment 9 for bug 1587892

Dry run support is added:
[root@nailgun ~]# fuel2 graph execute --env 1 --type customgraph --dry-run
Deployment was executed

Verified on:
cat /etc/fuel_build_id:
 455
cat /etc/fuel_build_number:
 455
cat /etc/fuel_release:
 9.0
cat /etc/fuel_openstack_version:
 mitaka-9.0