VOL-1334 : Fixed concurrency issues

- Semaphores were added at the different layers of the model
- Made the proxy interfaces more robust
- Eliminated problems while retrieving latest data in concurrent mode

Change-Id: I7854105d7effa10e5cb704f5d9917569ab184f84
diff --git a/db/model/utils_test.go b/db/model/utils_test.go
index c4cc60d..618e158 100644
--- a/db/model/utils_test.go
+++ b/db/model/utils_test.go
@@ -27,13 +27,13 @@
 		FirmwareVersion: "someversion",
 	}
 	b := &voltha.Device{}
-	Clone(reflect.ValueOf(a).Interface(), b)
+	clone(reflect.ValueOf(a).Interface(), b)
 	t.Logf("A: %+v, B: %+v", a, b)
 	b.Id = "12345"
 	t.Logf("A: %+v, B: %+v", a, b)
 
 	var c *voltha.Device
-	c = Clone2(a).(*voltha.Device)
+	c = clone2(a).(*voltha.Device)
 	t.Logf("A: %+v, C: %+v", a, c)
 	c.Id = "12345"
 	t.Logf("A: %+v, C: %+v", a, c)