Add link to git repo in footer

[Doug Hellmann]

Link to the cgit url for the repo hosting the docs

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/227299

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/227299
Committed: https://git.openstack.org/cgit/openstack/oslosphinx/commit/?id=efec9c68fe2fcc51c147c0b20228a57be60ff2db
Submitter: Jenkins
Branch: master

commit efec9c68fe2fcc51c147c0b20228a57be60ff2db
Author: Doug Hellmann <email address hidden>
Date: Thu Sep 24 13:21:42 2015 +0000

    add link to project source in navigation sidebar

    Change-Id: I841f0e63259d6b79c55b223c8e7266c8520a668d
    Closes-Bug: #1426898

[Alan Pevec (apevec)]

Followup fix https://review.openstack.org/227869

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/228361
Committed: https://git.openstack.org/cgit/openstack/oslosphinx/commit/?id=2525bb98d17c239e45342e4191bd946e74484a9e
Submitter: Jenkins
Branch: master

commit 2525bb98d17c239e45342e4191bd946e74484a9e
Author: Javier Pena <email address hidden>
Date: Mon Sep 28 10:56:05 2015 +0200

    Make urlparse import Python3-compatible

    urlparse moved to urllib.parse, so the current code fails in
    Python3. Using six to ensure compatibility.

    Related-Bug: #1426898

    Change-Id: I9297c886dcc361238e942cb8162f589072001094