update compute node with an SSH config that ignores known hosts file

Change-Id: Iaaf65a97bb8d8314ef6a1800b9484f291fa85567
diff --git a/roles/compute-node/files/config b/roles/compute-node/files/config
new file mode 100644
index 0000000..990a43d
--- /dev/null
+++ b/roles/compute-node/files/config
@@ -0,0 +1,3 @@
+Host *
+   StrictHostKeyChecking no
+   UserKnownHostsFile=/dev/null