Add "gerrit deletedraft".

BUG=None
TEST=Run manually on a draft patch set

Change-Id: I2b98729bfce62798a3b45326152ee4498afe96ba
Reviewed-on: https://chromium-review.googlesource.com/189183
Reviewed-by: Jon Salz <jsalz@chromium.org>
Commit-Queue: Jon Salz <jsalz@chromium.org>
Tested-by: Jon Salz <jsalz@chromium.org>
3 files changed