Ensuring all data on pod template is copied during combine

[farley13]

Really 3 things going on in this diff:

1. I found that setting idle timeout wasn't keeping slaves around - they'd get killed once each job finished. Tracking this down - it turned out combine ( PodTemplate, PodTemplate ) was creating a new object to copy data into but was copying an incomplete set of data in - dropping a number of fields. These are now copied in similar to the existing fields - preferring template over parent.
2. Added some logging in combine for PodTemplate to mimic what already existed for combine for Pod.
3. Added a simple unit test for the remaining non-deprecated fields on PodTemplate.