Don't proxy Gerrit's fake contactstore.

* modules/gerrit/templates/gerrit.vhost.erb: If the contactstore
feature is enabled, don't shadow the URL to the fakestore CGI with
the Gerrit loopback proxy.

Change-Id: Ic6d01d671b762370b91f732c1a980051cdb5f6c2
Reviewed-on: https://review.openstack.org/20053
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins