Show floating IP associated with Load Balancer VIP

Previously the code always tried to show an instance when
a floating IP is associated. This commit chnages the code
to consider a port device_owner associated with a floating IP
so that appropriate information is displayed in the table.

Change-Id: I5d99090b17bf94a80a0d7894ab2084f83e55d59d
Closes-Bug: #1359215
Merge "Show floating IP associated with Load Balancer VIP"