Fix concat file mode

The concat module passes the file permissions straight through to a file
resource, so for this to work in future parser then the mode has to be a
quoted string.

Change-Id: Iddfa6416e68127f874ce38edcdf1e208def2473f

manifests/storage/server.pp

@@ -101,7 +101,7 @@ define swift::storage::server(
     group   => $group,
     notify  => Service["swift-${type}", "swift-${type}-replicator"],
     require => Package['swift'],
-    mode    => 640,
+    mode    => '0640',
   }
 
   $required_middlewares = split(