VOL-1255: Fixed an issue with the proxy implementation

- Had to change the model slightly to mimic a polymorphic behaviour

Change-Id: I12017cdfedf5c0ed05243245aa2a811556222e0f
diff --git a/db/model/transaction_test.go b/db/model/transaction_test.go
index 3b1b5bf..45e6c2d 100644
--- a/db/model/transaction_test.go
+++ b/db/model/transaction_test.go
@@ -27,7 +27,7 @@
 )
 
 type transactionTest struct {
-	Root      *Root
+	Root      *root
 	Backend   *Backend
 	Proxy     *Proxy
 	DbPrefix  string
@@ -69,7 +69,7 @@
 
 	GetProfiling().Report()
 
-	tx.Proxy = tx.Root.Node.GetProxy("/", false)
+	tx.Proxy = tx.Root.GetProxy("/", false)
 }
 
 func Test_Transaction_1_GetDevices(t *testing.T) {