Pass withCredentials to ajaxTransport

[eablamb]

I have an application making cross-site requests to an API. For this to work, I need to pass withCredentials to the list of options to make a download request. However, the ajaxTransport to handle arraybuffers/blobs doesn't pass this option to the XHR it's creating.

I believe the fix would be simple, just collect the withCredentials option and assign it to the XHR. Thanks in advance.