Add support for not waiting for the DOM to be ready

Specifying a true value for "immediate" in the config makes it so whenReady immediately executes whatever it is passed.

I know this is not ideal and breaks the "golden rule".

However, we've run into instances where a customer's page takes a long time to be "ready" and therefore our application also loads slowly, which they then complain to us about.

We've been using this modification for many months now for all customers and have not had any issues.