Support range requests in the client's httpReadSeeker
Support range requests in the client's httpReadSeeker

Remove buffering on the reader, because it's not useful. Also remove
artificial io.EOF return.

Signed-off-by: Aaron Lehmann <8ecfc6017a87905413dcd7d63696a2a4c351b604@docker.com>

thaJeztah/distribution,thaJeztah/distribution