Fix floating ips with external gateway

If dnsmasq is configured to use an external gateway, then floating
ips on other interfaces do not work properly. This is because
outgoing traffic is no longer snatted to the floating ip.

This patch fixes it by adding an ebtables rule to force traffic
from ips that have a floating ip associated to route instead
of bridge.

Fixes bug 1096985

Change-Id: I8e4904660d42fe51c44b66686bed9f5d622693bd
Add version constraint for cinder

Cinder client usage requires the "retries" parameter introduced in
cinderclient-1.0.1. This should be a constraint in pip-requires.

Change-Id: I36e8a363c9d4bb7cc4ecfda85644fc4284f17471
Merge "Add version constraint for cinder"
Merge "Fix floating ips with external gateway"