Currently, when we gather test results from DUTs, we copy them
first from the DUT to the shard, then copy them from the shard
to GS.  We should consider just copying them directly from the
DUT to GS.

Pro:
  * This saves about half of the bandwidth we spend on results
    transmission.
  * This spares the shards the work of both the ingress _and_
    the egress bandwidth.

Con:
  * Copying from DUT to autoserv master will still be needed
    in some cases (esp. test_that), so we'd have to add a new
    code path without deleting any old code paths.
  * The shards still need selected bits of the data for results
    parsing, so the parsing code could get more complicated.
  * We'd have to include gsutil in test images.
  * We'd need to be able to tell the DUTs where to upload to.
  * We'd need to have a way to securely transmit credentials
    to DUTs (the shards would have to know and forward the
    information).