support updating container images as per kubectl set-image

[jcderr]

No description provided.

[aabed]

@brosner can you please take a look at this change, I believe it will be nice to have such a feature

[mvid]

Hey, I implemented this method in my product and it worked as expected. +1

[brosner]

I am a little concerned by this change for a couple of reasons:

1. image getter/setter is dealing with multiple images. The correct naming should be images IMO.
2. Implementing these methods on ReplicatedMixin is going to lead to misleading on expected behavior IMO. While we are just doing object updates, I'd like to try to avoid cases where every object inheriting from ReplicatedMixin would behave the same. For example, the only object that inherits from ReplicatedMixin that would behave like set-image (which is actually replica sets) is Deployment.

Due to this being an improved API over what is already possible, I'd like to punt to another release. I think there is merit in this change, but needs to be more thought through when exposing object attributes at the Python object namespace.