title: Botkit is not sending Generic Template (Attachments) facebook messenger
body: <p>I am trying to reply to the user with this message:</p>
  
  <pre><code>  bot.reply(message, {
                      "attachment":
                      {
                          "type": "template",
                          "payload": {
                              "template_type": "generic",
                              "sharable": true,
                              "elements": [
                                  {
                                      "title": "MY title of bd",
                                      "image_url": "https://storage.googleapis.com/ssfkj.com/undefined",
                                      "subtitle": "undefined/undefinedundefinedn(undefined)",
                                      "default_action": { "type": "web_url", "url": "https://ssfkj.com/profile", "messenger_extensions": true, "webview_height_ratio": "tall", "fallback_url": "https://ssfkj.com/profile" }
                                      , "buttons": [{ "type": "payload", "payload": "DEL__PA_undefined", "title": "View more" }
                                      ]
                                  }]
                          }
                      }
                  });
  </code></pre>
  
  <p>But the bot is sending nothing. What is wrong in my code?</p>