Update Horizon submodule to the latest

This includes major local_settings.py updates added during Havana.

Also set $fqdn to match the Horizon host, required when using Django
1.5 (see ALLOWED_HOSTS).

https://docs.djangoproject.com/en/1.5/ref/settings/#allowed-hosts

Change-Id: I2e428712bc3560e0fb9237c30e19f022fb612178
Merge "Update Horizon submodule to the latest"