nebraska: A lightweight mock of the Omaha server

Simple server that responds to POST requests with an error message and
echos the request body.

BUG=chromium:892450
TEST=Manual, unittesting

Change-Id: I1ab5f27eeae32f0da92f3d781897e4f5b1d4d89f
Reviewed-on: https://chromium-review.googlesource.com/1279130
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Colin Howes <chowes@google.com>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
3 files changed