Use Deployment with leader election instead of StatefulSet

Deployment behaves better when a node gets disconnected from the rest of
the cluster - new provisioner leader is elected in ~15 seconds, while
it may take up to 5 minutes for StatefulSet to start a new replica.

Refer: 52d1fbcf9d

Fixes: #335

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

deploy/rbd/kubernetes/csi-provisioner-rbac.yaml

@@ -87,6 +87,9 @@ rules:
   - apiGroups: [""]
     resources: ["configmaps"]
     verbs: ["get", "list", "watch", "create", "delete"]
+  - apiGroups: ["coordination.k8s.io"]
+    resources: ["leases"]
+    verbs: ["get", "watch", "list", "delete", "update", "create"]
 
 ---
 kind: RoleBinding