Horizon needs this selinux boolean set

See:
https://bugzilla.redhat.com/show_bug.cgi?id=978568
https://github.com/stackforge/packstack/blob/master/packstack/puppet/templates/horizon.pp

Change-Id: I1cbf181625bfcb3b23fd57d8342fb72743342ebc

manifests/horizon.pp

@@ -100,4 +100,11 @@ class openstack::horizon (
     django_debug          => $django_debug,
     api_result_limit      => $api_result_limit,
   }
+
+  if $::selinux {
+    selboolean{'httpd_can_network_connect':
+      value      => on,
+      persistent => true,
+    }
+  }
 }