Do not pass message to 'shutdown' command.
Do not pass message to 'shutdown' command.

Looks like on Mac '/sbin/shutdown -r now' is specified in sudoers file exactly
like that, without allowance for a message. As a result an attempt to reboot with
a message causes sudo prompt to pop up.

R=maruel@chromium.org
BUG=

Review URL: https://codereview.appspot.com/146730043

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