devapp: initial support for App Engine Flex

devapp now supports 3 modes of operation:

- App Engine Standard. This supports Go 1.6 and requires a modified
  local go-github to continue working. This app is built with the
  "appengine" build tag.

- App Engine Flex. This builds Go 1.8 in a Docker container, using the
  build tag "appenginevm", and works with the Google Cloud platform.

- Normal. This uses an in-memory datastore, and does not
  support user login/logout.

To get this working I copied appengine.go to noappengine.go and
modified the calls until they were working. You can view a running app

Change-Id: I8ea018e63baf2dafb44150f7eee419e09065ba2c
Reviewed-by: Brad Fitzpatrick <>
11 files changed