Notable changes here:
 * 'cipd' binary is now statically linked and doesn't depend of libc.so.
 * New 'cipd instances <pkg>' subcommand that list recently uploaded instances
   of a package.
 * cipd now properly removes empty directory trees if they are left after
   uninstalling some files.

R=iannucci@chromium.org
BUG=796320, 789750

Change-Id: Iebc5655640defbbef4a5fb1850aeb852746e5ef3
Reviewed-on: https://chromium-review.googlesource.com/835657
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>