Change executors interface to return event channels and allow to
to set event processors. In further development this will allow better
visibility in UI or in command line, also opens the room for concurency.
Also add kubeconfig provider interface that will return kubeconfig.File
object to provide uniform way of accessing kubeconfig
Change-Id: I47bf9409a9b4286905cd9fc4ce172ee33e16dfa6
696b287552