For now only affect gclient help to figure out if there is any issue with it.

Because of the way it's done, there is no way to disable coloring, which could
be annoying when redirected. This needs to be taken in consideration.

R=dpranke@chromium.org
TEST=manually tested on linux, cygwin and windows, both run manually and
redirected to a text file.
BUG=


Review URL: http://codereview.chromium.org/8365001

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@106708 0039d316-1c4b-4281-b951-d872f2087c98