Allow you to pass options from a Batman.Request to the adapter implement...

@hornairs @RichardBlair 

So Richy needed a way to set jQuery's `cache` option to `true`. We previously provided no mechanism with which to pass additional options to the underlying Ajax adapter. This allows you to do that. The only thing I don't like is that the node adapter doesn't really have any options it can take, nor even a method for parsing its options, so we have to special case it in the tests. Thoughts?