Expose and receive a range for resumable uploads

[xsawyerx]

At the moment, resumable uploads cannot properly continue if they're interrupted because we don't expose the range to the user when there's an error and we don't receive the range as an input parameter.

While using Futures would make this less problematic (you can store a callback to continue on an error and wait with it), it would still be good to be able to receive the range chunk you need to continue from.