Floating_ip create /31,32 shouldn't silent error
Floating_ip create /31,32 shouldn't silent error

Fixes bug 1017682 the netaddr.IPNetwork.iter_hosts
method doesn't return any IPs when /32 or /31 and
should throw an exception instead of silent error

Change-Id: Id8875b6016a4dbb40b29d2f7687e6c35491e0129

n0ano/ganttclient