More compression support.
More compression support.

R=maruel@chromium.org, vadimsh@chromium.org

BUG=

Review URL: https://codereview.appspot.com/194700043

madecoste/swarming,luci/luci-py,madecoste/swarming,luci/luci-py,pombreda/swarming,pombreda/swarming,madecoste/swarming,luci/luci-py,madecoste/swarming,pombreda/swarming,luci/luci-py,pombreda/swarming