gs_cache: add a temp URL handler for fake Omaha service

As a short term work around, we will split the /update RPC of
devserver.py out and temporarily mount it to gs_cache.

BUG=chromium:1078188
TEST=Tested manually.
  1. Started the service locally
    $ ./bin/gs_archive_server -p 8889 -c http://localhost:8889
  2. Tested by a POST request.
    $ curl -XPOST -H 'content-type:application/xml' -d '<?xml?><request/>'  http://localhost:8889/update/board/version/au_nton?full_update=True
    Fake Omaha: To be implemented
    Args: ('board', 'version', 'au_nton')
    kwargs: {'full_update': u'True'}
    Data: <?xml?><request/>

Change-Id: I6bbab30a6825da40d8d679e2a8f2c84c6266d744
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2227471
Reviewed-by: Sanika Kulkarni <sanikak@chromium.org>
Commit-Queue: Congbin Guo <guocb@chromium.org>
Tested-by: Congbin Guo <guocb@chromium.org>
Auto-Submit: Congbin Guo <guocb@chromium.org>
2 files changed