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/voltha/templates/freeradius.yaml b/voltha/templates/freeradius.yaml
index 8f9eaea..ef86b16 100644
--- a/voltha/templates/freeradius.yaml
+++ b/voltha/templates/freeradius.yaml
@@ -13,6 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+{{- if .Values.freeradius.enabled }}
 apiVersion: v1
 kind: Service
 metadata:
@@ -91,3 +92,4 @@
         - name: freeradius-config
           configMap:
             name: freeradius-config
+{{- end}}