ssh-hostkeys: Manage global SSH host key database

The *ssh-hostkeys* role is used to manage the global SSH host key
database. This file is consulted by the `ssh` command when verifying
remote host keys on first connect. If the host key is found here, it is
copied to the user's host key database file without prompting for
verification.

roles/ssh-hostkeys/tasks/main.yml

@@ -0,0 +1,5 @@
+- name: ensure global ssh host key database is populated
+  copy:
+    src=ssh_known_hosts
+    dest=/etc/ssh/ssh_known_hosts
+    mode=0644