Catch FloatingIpNotFoundForHost exception

When showing floating ips for a given host, the FloatingIpNotFoundForHost
exception isn't handled when no floating ips can be found for the host.
This patch fixes this bug.

Closes-Bug: #1289164
Change-Id: Ic25ffd66945fd40ba10d69515e0cbfeae840313c
Merge "Catch FloatingIpNotFoundForHost exception"