Switch to RHN; fix openshift.sh usage

Chapter 02, Subscription Management: Switch from using RHSM to using RHN
because RHSM isn't working on OS1 Public.

Chapter 03, Installation: Fix the usage of openshift.sh to use RHN instead
of RHSM, specify named_ip_addr for both hosts so that they get the correct
nameserver configured, and use the named_entries setting so that the
correct DNS records are created.