Run Horizon unit tests with Django 1.4 too.

Fixes bug 1183863.

* .../jenkins_job_builder/config/horizon.yaml: Add a new
gate-horizon-python27-django14 job which uses a separate tox
environment to force Django 1.4 instead of 1.5.

* .../zuul/layout.yaml: Run gate-horizon-python27-django14 on
horizon's master branch in the check and gate pipelines. Earlier
horizon stable releases pinned Django to 1.4 anyway and do not need
this additional job.

Change-Id: Ibdf273ff35124d33eeae97f7b4749c15b9c980f0
Reviewed-on: https://review.openstack.org/32884
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Reviewed-by: Julie Pichon <jpichon@redhat.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins
Pull in Russell's OpenStack Stats scripts.

Also, while at it, make a single core team that deal with this and
gitdm, because it's really largely the same people interested.

Change-Id: I60410c6e6efafe0b0417b70ece2e832240ab721b
Reviewed-on: https://review.openstack.org/33162
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Paul Belanger <paul.belanger@polybeacon.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins
Separate infra publications by branch name.

Change-Id: If44101b1eb909ad3e6c2ae6cb93e23c9de47ace7
Reviewed-on: https://review.openstack.org/33376
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins