This commits introduces the asyncio event loop as well as the base
abstract class to define watchers.
It is in a very simple approach (it does not reschedule watchers if
they fail) but it lets you to see the proposal of hierarchy in watchers
as well as the methods that a watcher has to implement (see the pod
module).
Partial-Implements: blueprint kuryr-k8s-integration
Co-Authored-By: Taku Fukushima <f.tac.mac@gmail.com>
Co-Authored-By: Antoni Segura Puimedon
Change-Id: I91975dd197213c1a6b0e171c1ae218a547722eeb
