I'm beginning to think doing chunked uploading from the JS side won't be possible; FileReader looks like it's limited to text and base-64 reading. Ouch! We need to do a binary split.

Could do a Java plugin just to do the chunked upload, but I'd say it's simpler to go without it. We can get upload progress now without chunked uploads with our patch to FileTransfer, and the retries on the cell network should generally cover for spotty connectivity unless it loses the connection entirely... in which case recovery is tricky if we don't know for sure where we left off.

We no longer need this for upload progress. Resolving as wont fix as we'd have to do the rest in java and make the app less portable.