remove iptables on cent

This might want revisited, or perhaps some attributes to control
whether or not we want strong iptables.  For now, we'll just drop
it.  If your swift network is a routable network, you have bigger
issues already.

Closes #50
Merge pull request #58 from rpedde-rcbops/issue-50

remove iptables on cent
Stop exim from acting as an open mail relay
Merge pull request #60 from andymcc/exim_relay

Stop exim from acting as an open mail relay

rcbops-cookbooks/swift-private-cloud/issues/33
Fix relay_hosts formatting on CentOS
Merge pull request #61 from andymcc/exim_centos

Fix relay_hosts formatting on CentOS
make exim relay nets overridable

fixes #62
Merge pull request #63 from rpedde-rcbops/issue-62

make exim relay nets overridable
don't default passwords

  * Remove defaults for keystone auth/admin accounts
  * Remove default for swift dispersion account
  * DRY up the keystone endpoint for dispersion conf
Merge pull request #69 from rpedde-rcbops/issue-59

don't default passwords