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/templates/etcd-cluster.yaml b/etcd-cluster/templates/etcd-cluster.yaml
new file mode 100644
index 0000000..281227f
--- /dev/null
+++ b/etcd-cluster/templates/etcd-cluster.yaml
@@ -0,0 +1,30 @@
+# 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.
+
+apiVersion: "etcd.database.coreos.com/v1beta2"
+kind: "EtcdCluster"
+metadata:
+  name: {{ quote .Values.clusterName }}
+spec:
+  size: {{ .Values.clusterSize }}
+  pod:
+    resources:
+      limits:
+        memory: {{ .Values.memoryLimit }}
+    etcdEnv:
+    - name: ETCD_AUTO_COMPACTION_RETENTION
+      value: {{ quote .Values.autoCompactionRetention }}
+    busyboxImage: {{ .Values.global.registry }}{{ .Values.images.busybox.repository }}:{{ tpl .Values.images.busybox.tag . }}
+  version: {{ tpl .Values.images.etcd.tag . }}
+  repository: {{ .Values.global.registry }}{{ .Values.images.etcd.repository }}