VOL-1247 : Modified change tuple to include previous and latest data

VOL-1214 : Fixed logs to use the proper mechanism

- Added missing license
- Moved one change tuple statement which would not include proper info

Change-Id: I5a02f6fe92c8b193642294d62f4413ac6edc0c62
diff --git a/db/model/root.go b/db/model/root.go
index a6c62c6..27e4ec4 100644
--- a/db/model/root.go
+++ b/db/model/root.go
@@ -18,7 +18,6 @@
 import (
 	"encoding/hex"
 	"encoding/json"
-	"fmt"
 	"github.com/google/uuid"
 	"github.com/opencord/voltha-go/common/log"
 	"reflect"
@@ -115,7 +114,6 @@
 	r.NotificationCallbacks = append(r.NotificationCallbacks, CallbackTuple{callback, args})
 }
 
-
 func (r *root) Update(path string, data interface{}, strict bool, txid string, makeBranch MakeBranchFunction) Revision {
 	var result Revision
 
@@ -246,7 +244,7 @@
 
 	start := time.Now()
 	if err := json.Unmarshal(blob.Value.([]byte), &data); err != nil {
-		fmt.Errorf("problem to unmarshal blob - error:%s\n", err.Error())
+		log.Errorf("problem to unmarshal blob - error:%s\n", err.Error())
 	}
 	stop := time.Now()
 	GetProfiling().AddToInMemoryModelTime(stop.Sub(start).Seconds())