Add etherpadlite server admin variable

The etherpad lite vhost template expects a server admin variable in the
etherpad_lite::apache manifest. Add one with a default of
webmaster@$fqdn.

Change-Id: Id974496ec330fa1453bc60d65518f4264f107da7

modules/etherpad_lite/manifests/apache.pp

@@ -2,6 +2,7 @@
 #
 class etherpad_lite::apache (
   $vhost_name = $::fqdn,
+  $serveradmin = "webmaster@${::fqdn}",
   $ssl_cert_file = '',
   $ssl_key_file = '',
   $ssl_chain_file = '',