VOL-1405 : First submission for read-only core

- Most of the logic was copied from the read-write implementation
- Added missing Get/List calls
- Added necessary targets in Makefile
- Added docker and k8s manifests

Amendments:

- Removed more unecessary code.
- Removed refs to kafka
- Adjustements to reflect comments
- Removed refs to kafka in manifests

Change-Id: Ife2ca13d3ae428923825f7c19d42359d60406839
diff --git a/protos/voltha.proto b/protos/voltha.proto
index f2f885f..faf57a1 100644
--- a/protos/voltha.proto
+++ b/protos/voltha.proto
@@ -88,7 +88,7 @@
 
 message CoreInstances {
     option (yang_message_rule) = CREATE_BOTH_GROUPING_AND_CONTAINER;
-    repeated string items = 1;
+    repeated CoreInstance items = 1;
 }
 
 // Voltha represents the Voltha cluster data.  Each Core instance will hold a subset of
@@ -105,9 +105,11 @@
 
     repeated Device devices = 4 [(child_node) = {key: "id"}];
 
-    repeated DeviceGroup device_groups = 5 [(child_node) = {key: "id"}];
+    repeated DeviceType device_types = 5 [(child_node) = {key: "id"}];
 
-    repeated AlarmFilter alarm_filters = 6 [(child_node) = {key: "id"}];
+    repeated DeviceGroup device_groups = 6 [(child_node) = {key: "id"}];
+
+    repeated AlarmFilter alarm_filters = 7 [(child_node) = {key: "id"}];
 
     repeated
         omci.MibDeviceData omci_mib_database = 28