make use of github optional

this attempts to pull out all the upstream github creation into a
single function, which can be disabled for environments that don't
want to do project creation up to github.

Change-Id: Ic65eb9c0070c50d0f05305a1c93d31d8afe09c2b
Reviewed-on: https://review.openstack.org/28213
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins