Correct gate-horizon-python27-django14 job.

* .../jenkins_job_builder/config/horizon.yaml: The job-template
named gate-horizon-python27-django14 was supposed to have been a job
instead, not a template. This corrects it so that the job will
actually exist rather than being an unused template definition.

Change-Id: I78ffb27fc6abd20b82e5c83a1f518e42060e0def
Reviewed-on: https://review.openstack.org/35149
Reviewed-by: Monty Taylor <mordred@inaugust.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins