Add option to restart usb on device status check before performing check.

Restart USB has been known to bring back offline devices. Add option to device
status check to restart usb ports before performing the check. This requires
restart_usb to be installed (see
https://code.google.com/p/chromium/issues/detail?id=305769). Prints warning if
the utility has not been installed on the host.

We will add this first to perf bots. Restarting usb has fixed device issues on these bots. If we find it works and does not have unseen consequences, we will deploy on all bots (i.e. make default of --restart-usb to True).

BUG=299891

Review URL: https://codereview.chromium.org/26747004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229553 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229553