Do not show db or site quota when the sites module is not active

Cherry-picked from !825 after master change.

Author: helmo

interface/web/dashboard/dashlets/databasequota.php

@@ -11,6 +11,11 @@ function show() {
                        return;
                }
 
+		$modules = $_SESSION['s']['user']['modules'];
+		if (!in_array($modules, 'sites')) {
+			return '';
+		}
+
 		$tpl = new tpl;
 		$tpl->newTemplate("dashlets/templates/databasequota.htm");
 

interface/web/dashboard/dashlets/quota.php

@@ -11,6 +11,11 @@ function show() {
 				return;
 		}
 
+		$modules = $_SESSION['s']['user']['modules'];
+		if (!in_array($modules, 'sites')) {
+			return '';
+		}
+
 		$tpl = new tpl;
 		$tpl->newTemplate("dashlets/templates/quota.htm");