Dependency fix in apache::listen::no_global_listen.

We were missing a dependency on the httpd package being installed,
and could thus try to comment out Listen directive(s) in httpd.conf
before the file existed.  Fix this.

manifests/listen.pp

@@ -50,6 +50,7 @@ class apache::listen::no_global_listen
 	'apache::listen::no_global_listen':
 	    file => $apache::configfile,
 	    pattern => '^\s*Listen(\s|$).*$',
-	    comment => '##--';
+	    comment => '##--',
+	    require => Class[apache::base];
     }
 }