Adds support for shutting down action clients (#69)

Author: manzato

src/lib/ActionClient.js

@@ -138,6 +138,24 @@ class ActionClient extends EventEmitter {
     });
     return id;
   }
+
+  /**
+   * Shuts down this ActionClient. It shuts down publishers, subscriptions
+   * and removes all attached event listeners.
+   * @returns {Promise}
+   */
+
+  shutdown() {
+    this.removeAllListeners();
+
+    return Promise.all([
+      this._goalPub.shutdown(),
+      this._cancelPub.shutdown(),
+      this._statusSub.shutdown(),
+      this._feedbackSub.shutdown(),
+      this._resultSub.shutdown()
+    ]);
+  }
 }
 
 module.exports = ActionClient;