Description of problem:
Creating a VM with PVC fails with the error `Failed to provision volume with StorageClass "glusterfs-storage": not able to parse your claim Selector` in PVC events.
PVC spec:
```
[cloud-user@cnv-executor-vatsal-master1 ~]$ oc get pvc saul-nassif-example-com-claim-1 -o yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  annotations:
    volume.beta.kubernetes.io/storage-provisioner: kubernetes.io/glusterfs
  creationTimestamp: 2019-04-08T07:02:49Z
  finalizers:
  - kubernetes.io/pvc-protection
  name: saul-nassif-example-com-claim-1
  namespace: default
  resourceVersion: "3476464"
  selfLink: /api/v1/namespaces/default/persistentvolumeclaims/saul-nassif-example-com-claim-1
  uid: 523adbc5-59cc-11e9-bdca-fa163e387aec
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1G
  selector: {}
  storageClassName: glusterfs-storage
  volumeMode: Filesystem
status:
  phase: Pending
```

Version-Release number of selected component (if applicable):
plugin master

How reproducible:


Steps to Reproduce:
1.Create a Host with a PVC
2.
3.

Actual results:
Creates a PVC but with a empty selector

Expected results:
Should not have the selector field if there are no selector

Additional info: