Refactor PodStatus to PodCondition in internal API for v1beta3

Change PodStatus (string) to PodCondition (string) to make space for new PodStatus (struct) in v1beta3 API.

Change the constant values for Pod statuses to match v1beta3 API.
Need to check exit codes of containers in above loop. If you don't want to handle that right now, then need to default to failed. Succeeded is rarer than failed, I think.