Decorative keys mixin

This mixin is really simple, it make your function_field_name value everything decorative, if the function name is authenticate_user then the request will look like:

let api = new RequestHandler("/<url_to_api>/");

api.PostSync({"action": "authenticate_user"});

With decorative keys the request can be:

let api = new RequestHandler("/<url_to_api>/");

api.PostSync({"action": "authenticate_user"});
api.PostSync({"action": "authenticate user"});
api.PostSync({"action": "authenticate-user"});
api.PostSync({"action": "authenticate:user"});