const login =  this.restangular.one('/api/admin/login').customPOST(
          { username: this.username, password: this.password},
          '',
          {},
          {
              'ContentType': 'application/json',
          }
      ).subscribe($response => {
          console.log($response.data.data);
          console.log(login);
      }, $error => {
          console.log($error);
      });