* Use a sensible default for k8s merge_type
The sensible default for merge_type is `['strategic-merge', 'merge'].
However, we can't make this the default default, as we need to support
users who are using openshift 0.6.0, where the merge_type parameter is
unsupported.
* Refactor k8s test suite for merge_type tests
Allow tests with pre-merge-type openshift and post-merge-type
openshift.
