fix(web): set proper format for phoenix controllers

Also remote the custom `namespace` option.

lib/wabanex_web.ex

@@ -20,7 +20,7 @@ defmodule WabanexWeb do
   def controller do
     quote do
       use Gettext, backend: WabanexWeb.Gettext
-      use Phoenix.Controller, namespace: WabanexWeb
+      use Phoenix.Controller, formats: [:json]
 
       import Plug.Conn
       alias WabanexWeb.Router.Helpers, as: Routes