allow user to pass ajaxOptions directly to ajax request

Here's a request that allows the field ajaxOptions to be passed to the ajax request.  Please let me know if you might consider it.  I'm using this with with chartkick-remote and this gist https://gist.github.com/dontfidget/1ad9ab33971b64fe6fef, which allows me to limit the number of concurrent remote requests.

My controller then has this code:

```
  include Chartkick::Remote
  chartkick_remote ajaxOptions: {queue: true, queueMaxConcurrency: 2}

```

I've also taken your suggestion and made remote requests the default behavior for views on controllers that call `chartkick_remote`.  Definitely looks better. Thanks.