Fix autoloader fatal errors from class reorganization

[MegaphoneJon]

This is intended to fix some autoloader issues I experienced regarding the recent reorganization. Ping @eileenmcnaughton.

[eileenmcnaughton]

This looks like a bug I introduced when adding those new actions. In response to reviewer feedback I moved the files into a subdirectory ('Query') but did not update this place in the code to reflect that. I think this should be merged

[judgej]

Thanks Barry, was just about to look at this.

As an aside, instead of '\Omnipay\AuthorizeNet\Message\Query\QueryRequest' I tend now to use the \Omnipay\AuthorizeNet\Message\Query\QueryRequest::class form, which can usually be shortened by context in the file it's used in to something like Message\Query\QueryRequest::class. There aren't any downsides in doing this, are there? Using the ::class modifier gives the fully qualified class name, but without the leading \, which works fine here.