This change adds to the multistrap playbook to ensure that the
hostname files are correct when multistrap installs packages. This
can be an issue when installing packages such as ssmtp. A later step
will override the hosts and hostname files so these changes will be
temporary in the overall build process.
Change-Id: I61124a4e991e4aaedadc9c6ef211b574178fb411
2a70f431cc