If a host is a member of the 'futureparser' group, pass the
'futureparser' option to the puppet role, which will turn on parser =
future in puppet.conf when manage_config is true and when the node isn't
already using puppet 4. Nodes can be added one at a time by adding them
to modules/openstack_project/files/puppetmaster/groups.txt.
Depends-On: https://review.openstack.org/572856
Change-Id: I54e19ef6164658da8e0e5bff72a1964b88b81242