This change implements yamllint and adjusts all yaml files to abide by our linting setup. This excludes config.template.yml as this will be done in an alternate commit.
This PR achieves the following goals:
* Utilise upstream version of kind instead of a patched version which allows binding to networks other than the default "kind"
* Utilises the registry cache which is setup one level above the kind cluster
The former point was required to successfully run our integration tests in a Kubernetes environment, however this is now possible without running a patched version of kind.
The second point is because DockerHub has introduced rate limiting for container downloads. If there are a large number of CI jobs nodes may occasionally be rejected due to the Kubernetes suite not pulling down from the registry cache.
