Support for `imagePullPolicy`

[surajssd]

Lot of configurations from fabric8, helm chart repo; I saw had this option specified explicitly and it was not just set to Always, the values were different. Can we add support for this in OpenCompose?

$ kubectl explain deployment.spec.template.spec.containers.imagePullPolicy
FIELD: imagePullPolicy <string>

DESCRIPTION:
     Image pull policy. One of Always, Never, IfNotPresent. Defaults to Always
     if :latest tag is specified, or IfNotPresent otherwise. Cannot be updated.
     More info: http://kubernetes.io/docs/user-guide/images#updating-images

Information about imagePullPolicy.

[pradeepto]

Adding link from the duplicate issue for posterity. https://kubernetes.io/docs/concepts/containers/images/