Update subcommand to support examples, always disable format_description and
format_epilog and add colors when enabled.

R=iannucci@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/22824018

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@218180 0039d316-1c4b-4281-b951-d872f2087c98