Fix docker config handling in offline installer

This fixes adding of dns address to
/etc/docker/daemon.json to always use infra's ip address
instead of possibly using it's hostname.
Also similar change is done in handling of
/etc/resolv.conf in infrastructure.yml.
Ip address is specified by the "cluster_ip" variable placed on a host.
Inventory specifies ip for everything except resource server (just for consistency).

Change-Id: I2baa3f4c7d69b8dff109b5f8ae984134caf2af7d
Issue-ID: OOM-1573
Signed-off-by: Michal Zegan <m.zegan@samsung.com>
diff --git a/ansible/infrastructure.yml b/ansible/infrastructure.yml
index 789f871..709a351 100644
--- a/ansible/infrastructure.yml
+++ b/ansible/infrastructure.yml
@@ -4,7 +4,7 @@
   tasks:
     - name: Setup resolv.conf
       lineinfile:
-        line: "nameserver {{ hostvars[groups.infrastructure[0]].ansible_host }}"
+        line: "nameserver {{ hostvars[groups.infrastructure[0]].cluster_ip }}"
         path: /etc/resolv.conf
         state: present
         insertbefore: BOF