etcd cluster chart and usage in voltha requirements

Addition of a chart dedicated to creating etcdCluster CRD instances from an already installed etcd-operator
This is good for specifying custom etcd images, retention periods, and custom repo locations.
Also helpful in installing instances of an etcdCluster separate from installing etcd-operator

Modify the voltha chart to require the etcd-cluster chart rather than etcd-operator, given the etcd instance is whats truly required.
This allows the upgrade/removal of voltha to take its etcd-cluster with it, without removing etcd-operator.

Update the voltha chart to make the inclusion of freeradius optional and remove unused consul config references.

Tested by running:
helm install -n cord-kafka incubator/kafka --set persistence.enabled=false --set zookeeper.persistence.enabled=false
helm install -n etcd-operator stable/etcd-operator

  wait for etcdclusters CRD to be created...

helm dep update ~/source/helm-charts/voltha
helm install -n voltha ~/source/helm-charts/voltha

Change-Id: I7001943d74fdbd38f4d786982c70908ba24fd0ca
diff --git a/etcd-cluster/values.yaml b/etcd-cluster/values.yaml
new file mode 100644
index 0000000..764c7e8
--- /dev/null
+++ b/etcd-cluster/values.yaml
@@ -0,0 +1,33 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Default values for etcd-cluster.
+# This is a YAML-formatted file.
+# Declare variables to be passed into your templates.
+
+clusterName: "etcd-cluster"
+clusterSize: 3
+memoryLimit: 1024Mi
+autoCompactionRetention: "12"
+
+images:
+  etcd:
+    repository: "quay.io/coreos/etcd"
+    tag: "3.2.18"
+  busybox:
+    repository: "busybox"
+    tag: "1.28.1-glibc"
+
+global:
+  registry: ""