Set correct HTTP proxy when running gsutil

Gsutil disregards the environment variable http_proxy and only reads
proxy settings from the boto configuration file. This CL allows our GS
library to read http_proxy and then overrides the proxy settings when
running gsutil using '-o'.

BUG=chromium:318478
TEST=unittest, cros lint

Change-Id: I25dff79291fe46eb2852bdf16f25665896dec739
Reviewed-on: https://chromium-review.googlesource.com/179326
Reviewed-by: Yu-Ju Hong <yjhong@chromium.org>
Commit-Queue: Yu-Ju Hong <yjhong@chromium.org>
Tested-by: Yu-Ju Hong <yjhong@chromium.org>
2 files changed