Mejora codigo smsgateway.

se añade llamado de parametro configuracion

src/BackendBundle/Controller/EnvioSmsController.php

@@ -66,7 +66,7 @@ class EnvioSmsController extends Controller {
         $response = new Response(
         $resp,
         Response::HTTP_OK,
-        ['content-type' => 'text/html']
+        ['content-type' => 'application/json']
         );
         
         return $response;