Confirmation on item deletion.

Signed-off-by: Min Chen <minchnew@gmail.com>
Fix a bug where a failed port add operation will crash the backend
server.

Interface won't be assigned a correct OpenFlow port number if the
port add operation isn't successful.

Signed-off-by: Min Chen <minchnew@gmail.com>
Physical Switch info can be fetched and displayed.

Signed-off-by: Min Chen <minchnew@gmail.com>