Avoid trying tearing down NS

[mogren]

Issue #641

Description of changes:
When deleting a deleted pod, we should not call TeardownNS

• Added Trace logging of pod events
• Check for IP before trying to tear down network namespace

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[nithu0115]

Thanks for the fix @mogren. I am custom built CNI running in my cluster that include this commit over night. So far, I do not see issues ( pod to pod connectivity or pod to coreDNS connectivity or pod to external service connectivity or missing rules as mentioned on #641 ) .