Refactor protocol buffer to split models into different packages

Change-Id: I26152ba227ebe9afd871c6e501ccca17c49e1e4e
diff --git a/incubator/rpc-grpc/src/main/proto/DeviceService.proto b/incubator/rpc-grpc/src/main/proto/DeviceService.proto
index 5ae7cd6..9ff86c5 100644
--- a/incubator/rpc-grpc/src/main/proto/DeviceService.proto
+++ b/incubator/rpc-grpc/src/main/proto/DeviceService.proto
@@ -1,15 +1,17 @@
 syntax = "proto3";
 option java_package = "org.onosproject.grpc.net.device";
 
-import "models/Device.proto";
-import "models/Port.proto";
+import "net/device/DeviceDescriptionProto.proto";
+import "net/device/PortDescriptionProto.proto";
+import "net/device/PortStatisticsProto.proto";
+import "net/device/DeviceEnumsProto.proto";
 
 package Device;
 
 message DeviceConnected {
   // DeviceID as String DeviceId#toString
   string device_id = 1;
-  DeviceDescription device_description = 2;
+  net.device.DeviceDescriptionProto device_description = 2;
 }
 
 message DeviceDisconnected {
@@ -20,26 +22,26 @@
 message UpdatePorts {
   // DeviceID as String DeviceId#toString
   string device_id = 1;
-  repeated Port.PortDescription port_descriptions= 2;
+  repeated net.device.PortDescriptionProto port_descriptions= 2;
 }
 
 message PortStatusChanged {
   // DeviceID as String DeviceId#toString
   string device_id = 1;
-  Port.PortDescription port_description= 2;
+  net.device.PortDescriptionProto port_description= 2;
 }
 
 message ReceivedRoleReply {
   // DeviceID as String DeviceId#toString
   string device_id = 1;
-  MastershipRole requested = 2;
-  MastershipRole response = 3;
+  net.device.MastershipRoleProto requested = 2;
+  net.device.MastershipRoleProto response = 3;
 }
 
 message UpdatePortStatistics {
   // DeviceID as String DeviceId#toString
   string device_id = 1;
-  repeated Port.PortStatistics port_statistics = 2;
+  repeated net.device.PortStatisticsProto port_statistics = 2;
 }
 
 message RegisterProvider {
@@ -72,7 +74,7 @@
 message RoleChanged {
   // DeviceID as String DeviceId#toString
   string device_id = 1;
-  MastershipRole new_role = 2;
+  net.device.MastershipRoleProto new_role = 2;
 }
 
 message IsReachableRequest {