This is Windows counterpart to https://chromium-review.googlesource.com/1171957

Also cleanup code style in cipd.ps1 script. It appears the common convention
for global variables in PowerShell is $GlobalVar and for locals is $localVar.

R=nodir@chromium.org, iannucci@chromium.org
BUG=870166

Change-Id: Ib8ffbad85497db31f7f5d44fdca6ed843e56f220
Reviewed-on: https://chromium-review.googlesource.com/1175248
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>
Reviewed-by: Nodir Turakulov <nodir@chromium.org>