Bug 7780 : NAT RPC's for getting SNAT/DNAT translation information.

Bug 7780 : NAT RPC's for getting SNAT/DNAT translation information.

Description : With the Current DS structure, it's is bit difficult to
identify information about what is the current DNAT/SNAT configuration
done fo the given router-uuid/vpn-uuid.

It would be good if we have a RPC's which can provide a information as
below.

input- router-uuid/vpn-uuid

SNAT output - router-name, internal-ip/port, external-ip/port,protocol
DNAT output - router-name,internal-ip,floating-ip

Change-Id: I00b6576d2a752b53e94ad28c611a06794c65456c
Signed-off-by: cgowdru <chetan.arakere@altencalsoftlabs.com>