Custom Request Function

by default the library supports `JQuery`, `vue-resource` and `axios` as ajax libraries.

If you wish to use a different library, or somehow alter the request (e.g add auth headers, or manipulate the data) use the `requestFunction` option. E.g:

options: {
    requestFunction(data) {
        return axios.get(this.url, {
            params: data
        }).catch(function (e) {
            this.dispatch('error', e);
        });
    }
}

When using a custom request function, the `url` prop is not required.