feature: allow sending silent notifications

src/types/Base.js

@@ -81,6 +81,15 @@ export default class Base extends EventEmitter {
     return bot.api[this.method](this.properties);
   }
 
+  /**
+   * Set disable_notification property to true (send a silent notification)
+   * @returns {object} returns the message object
+   */
+  disableNotification() {
+    this.properties.disable_notification = true;
+    return this;
+  }
+
   /**
    * Returns properties of the object
    * @return {object} properties of object