Refactor this logic so that it can be more easily tested and expanded
without cluttering the pod.go file. Additionally, add some safe guards
around the pod cast to ensure that we're working with pods before we
pass them.
Check if the Pod is actionable before taking NetworkPolicy actions which
includes both adding KUBE-POD-FW and KUBE-NWPLCY chains for it.
Checks have now been consolidated to a single isNetPolActionable()
function which checks for pod phases that we don't want NetworkPolicy
for like: Failed, Completed, and Succeeded, missing pod IP addresses,
and pods with HostNetwork enabled.
fixes#1056
