Adjust registration request to match current apiserver api

I was getting `error registering` errors from kube-register until `metadata.name` were introduced on kube-register side.

    Nov 13 23:50:27 ip-10-21-2-147.eu-west-1.compute.internal kube-register[25777]: error registering: 10.21.2.146: {"kind":"Status","creationTimestamp":null,"apiVersion":"v1beta1","status":"Failure","message":"minion \"\" is invalid: name: required value ''","reason":"Invalid","details":{"kind":"minion","causes":[{"reason":"FieldValueRequired","message":"name: required value ''","field":"name"}]},"code":422}