Fix $httpd::vhost::proxy::servername parameter

The $httpd::vhost::proxy::servername parameter was not being used, and
the local variable $srvname was defaulting to the name of the defined
type. This patch copies the logic from httpd::vhost to conditionally
set $srvname to the $servername parameter if it is set, and default to
the old behavior if not.

Change-Id: I4936be856db1a1af279b7c3824606e2c0375e9a6

manifests/vhost/proxy.pp

@@ -33,7 +33,11 @@ define httpd::vhost::proxy (
 
   $apache_name = $httpd::params::apache_name
   $ssl_path = $httpd::params::ssl_path
-  $srvname = $name
+  if $servername == '' {
+    $srvname = $name
+  } else {
+    $srvname = $servername
+  }
 
   if $ssl == true {
     include httpd::ssl