* Changes in sonic-buildimage for the NAT feature
- Docker for NAT
- installing the required tools iptables and conntrack for nat
Signed-off-by: kiran.kella@broadcom.com
* Add redis-tools dependencies in the docker nat compilation
* Addressed review comments
* add natsyncd to warm-boot finalizer list
* addressed review comments
* using swsscommon.DBConnector instead of swsssdk.SonicV2Connector
* Enable NAT application in docker-sonic-vs
