Just thought I'd throw this out there as a possible bug...  I'm running 
RHEL 7.1 and OpenStack Kilo RDO.
It seems that when I terminate an instance through Horizon that has an 
associated floating IP, the floating IP is *not* disassociated upon the 
instance's termination.  I have to manually disassociate the floating ip 
after I terminate the instance through Horizon via:
neutron floatingip-disassociate e28051c5-7fb1-4887-ade9-f1b062523ad7
for example.  Then it frees up.  Back when I was playing with the 
Icehouse release of RDO OpenStack, the floating IPs were released 
automatically when I terminated an instance through Horizon, so I was 
surprised when I did not see the same behaviour here.
[root@os-con-01 ~]# rpm -q python-django-horizon
python-django-horizon-2015.1.0-5.el7.noarch
Just a heads up...
cheers,
erich