Update to Havana version of Horizon

DHC-1476

This update includes:
* Switch from quantum to neutron
* Update url to match new django 1.5 syntax

Change-Id: Iee2c699d737fb7433523b21d037ec7322ff4748e
Signed-off-by: Rosario Di Somma <rosario.disomma@dreamhost.com>
Merge pull request #24 from rodis/master

Update to Havana version of Horizon