test for pcn-k8s related components are missing

[mauriciovasquezbernal]

Testing for pcn-k8s related components is badly missing, so it is common to have problems like #100.

In order to avoid breaking pcn-k8s we should:

• create tests for pcn-k8switch and pcn-k8sfilter services.
• create a test (maybe based on vagrant) for the full solution: pod to pod, pod to service, external services and so on.
• create tests for the pcn-k8s agent.