[EoS] Fetcher fixes

When testing end-to-end, found some problems with the Fetcher:
* POST is not accepted by the server, converted to GET (using query
  params)
* URL was not set in the request
* URL utils had a bug causing "/v1/" to be missing from the path.

Bug: 867488
Change-Id: Ie60010bc45ac67923d211bce2a84248186f2dbc0
Reviewed-on: https://chromium-review.googlesource.com/1247021
Reviewed-by: Cathy Li <chili@chromium.org>
Commit-Queue: Justin DeWitt <dewittj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594484}
3 files changed