Introduce an openshift_node template that serves as base for all
openshift services. This reworks the inventory files so that hosts are
defined once and made part of the appropriate groups.
The master node can now be split from the infra node, or bundled
together with the Worker in the all-in-one role.
Provide environment files to enable the Master, Worker, Infra or
all-in-one role individually.
Change-Id: I9ad86185b01c88b609d320e2384c5644bd99bdae
7373adc72e