public function login(Request $request)
 {
     $user = str_replace("\"", "", str_replace("'", "", $request->input('usuario')));
     $pass = sha1(str_replace("\"", "", str_replace("'", "", $request->input('pass'))));
     $usuario = Usuario::login($user, $pass);
     if (count($usuario) != 0) {
         \Session::put('logeado', true);
         \Session::put('usuario', $user);
         \Session::put('id_usuario', $usuario[0]->id);
         \Session::put('carrito', array());
         \Session::put('total_compra', 0);
         return \Redirect::back();
     } else {
         return \Redirect::back()->with(array('error_login' => true));
     }
 }