Remove null from image field and add image into required for deployment container and init container

[khtee]

Image is a required value when creating a deployment. Adding this check into schema to catch the error when there is no image field.

Following is the error received when performing kubectl apply.

Error in creating Deployment YAML on kubernetes 
spec.template.spec.containers[1].image: Required value
spec.template.spec.containers[2].image: Required value

[yannh]

Hi @khtee , thanks for the contribution! All these schemas are automatically generated using this script https://github.com/yannh/openapi2jsonschema here: https://github.com/yannh/kubernetes-json-schema/blob/master/build.sh

If you found an issue, it's likely a bug in the openapi2jsonschema script... any chance you could have a look? I would not merge "manual" changes to the generated schemas 😞 but happy to regenerate them if we can fix the script!