Add Support for Batch Requests

[ChayimZaklad]

Please add a feature to this framework to enable submitting batch requests to the API.

I'm referring to what's documented in Amazon's Product Advertising API Developer Guide, starting page 71, Batch Requests (enabling 2 different requests to be sent simultaneously and responded to simultaneously).

It would enable REST requests, for example, to use

Operation.1.ParameterName=ParameterValue
Operation.2.ParameterName=ParameterValue
Operation.Shared.ParameterName=ParameterValue

This would enable, for example, getting 2 consecutive pages totaling 20 products, without waiting 1 second between requests. (I'd need it to work with SOAP requests, too.)

[Exeu]

Will be implemented in version 2 d74457c#diff-a217f36772a14f1eb1df57cac606d90dR1