Drop subscription-manager and Extras repo enablement for RHEL

This broke my use of k-a because due to the way Ansible works, even if
the hosts are already subscribed, it's required to create the
`rhn_username` files on each host.

Everyone using RHEL should understand how to set up subscriptions.
(If they don't, we've failed)

That said there might be a case for sanity checking that the Extras
repo is enabled...but on the other hand things will quickly error out
due to missing packages, and that's hopefully obvious.

README.md

@@ -16,6 +16,13 @@ Record the IP addresses of the machines you want to be your minions.
 
 Stick the system information into the 'inventory' file.
 
+Ensure that RHEL machines are properly subscribed to subscription
+management.  For more information, see
+https://access.redhat.com/documentation/en-US/Red_Hat_Subscription_Management/
+
+You must also ensure that for yum-managed non-Atomic hosts that the
+Extras repository is enabled: `subscription-manager repos --enable rhel-7-server-extras-rpms`
+
 ###  Set up ssh access via public keys
 
 See the `pre-setup/` directory.
@@ -33,9 +40,6 @@ You already did the config!  Just run the setup::
 
 This works on RHEL7, Atomic, F20, F21 and rawhide.
 
-For RHEL7 it will set up rhn subscriptions.  Put your username in a file named
-`~/rhn_username`.  Put your rhn password into a file named `~/rhn_password`.
-
 When DNS setup is enabled, it may take some time for Kubernetes (and Docker
 inside) to download the images and start the DNS pod. Watch `kubectl get pods`
 to see when `kube-dns-*` pod enters `Running` state. Try to resolve

roles/common/tasks/main.yml

@@ -19,9 +19,6 @@
   failed_when: false
   changed_when: false
 
-- include: rhel7_repos.yml
-  when: is_rhel7.rc == 0
-
 - name: Determine if firewalld installed
   command: "rpm -q firewalld"
   register: has_firewalld