CORD-1151
Make cord_dir and cord_profile_dir local to config node
use head_* and config_* prefixes to avoid hardcoding paths
config-side ssh key generation+
fix frontend & mock builds
[build] group in inventory
fix inventory strangeness
raise privs when creating ssh_pki_dir
move admin-openrc.sh.j2 to cord-profile
add copy-cord-playbook.yml, clarify where it runs
fix paths for head_cord_profile_dir with mock/frontend
use /opt/cord_profile/admin-openrc.sh rather than ~/admin-openrc.sh
install pki
make comment in do-enlist-compute-node accurate, set correct interface
remove hardcoded credential path
logging and ssh key fixes

Change-Id: Ie7560c911dce1558e09806c9997884dfbd475e9c
diff --git a/prep-platform-playbook.yml b/prep-platform-playbook.yml
index 8661208..d2f9943 100644
--- a/prep-platform-playbook.yml
+++ b/prep-platform-playbook.yml
@@ -20,15 +20,16 @@
     - apt-cacher-ng
 
 - name: Configure all hosts to use DNS server
-  hosts: all
+  hosts: head, compute
   become: yes
   roles:
     - { role: dns-configure, when: not on_maas }
 
 - name: Prep systems
-  hosts: all
+  hosts: head, compute
   become: yes
   roles:
     - common-prep
+    - pki-install
     - { role: cloudlab-prep, when: on_cloudlab }