CLOUDSTACK-2604 Fixed deleting secondary ip when no PF rules set

Signed-off-by: Abhinandan Prateek <aprateek@apache.org>
CLOUDSTACK-2650 setting vm ip null in user_ip_address when static nat ip

Signed-off-by: Abhinandan Prateek <aprateek@apache.org>
meng's proposal for GSOC2013