Use a CentOS 7 base image for the tf-operator image (#469)
Use a CentOS 7 base image for the tf-operator image (#469)

* Use a CentOS base image for the tf-operator image

* Remove comment about golang-alpine (doesn't apply)

* Install golang from an rpm rather than a url

* Resolve pylint errors in release and release_test

kubeflow/training-operator,kubeflow/training-operator,kubeflow/training-operator