Cryptic ClassCastException in f-m-p when host verification fails on Openshift

f-m-p is trying to detect openshift by sending an http requests to query all the root paths. If for any reason this request fails (e.g. ssl related reasons, network issues) f-m-p is considering the cluster to be vanilla kubernetes (and will use an instance of DefaultKubernetesClient). However, if the user has requested openshift mode then it will cast the DefaultKubernetesClient to OpenshiftClient leading to a class cast exception.

We need to provide a more acurate error messsage to the user that indicates the real problem.