Fix large uploads (#1910)
Fix large uploads (#1910)

- Because of weird mod_zip problems, we proxy requests twice - so need to increase the limit in both cases.
- Increase the limit to 10G instead of 8M.
- Don't buffer the uploads.
- Don't intercept errors; that was just a copy/paste bug - we should return S3 errors directly.
quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt,quiltdata/quilt-compiler,quiltdata/quilt,quiltdata/quilt-compiler