Add task/goal to set up private container registry credentials.

[coollog]

Background:

Minikube (kubernetes) requires credentials to pull images from private container registries. These credentials need to be provided using the method described in https://github.com/google/jib/#i-am-seeing-imagepullbackoff-on-my-pods-in-minikube.

Proposal:

Add new task/goal (Maven/Gradle) for setting up these credentials in the minikube k8s cluster.

[coollog]

See https://github.com/kubernetes/minikube/blob/master/docs/insecure_registry.md