Move Login business logic from gRPC API to Accountmanager (#713)

The Management gRPC API has too much business logic 
happening while it has to be in the Account manager.
This also needs to make more requests to the store 
through the account manager.

management/server/status/error.go

@@ -31,6 +31,9 @@ const (
 
 	// BadRequest indicates that user is not authorized
 	BadRequest Type = 9
+
+	// Unauthenticated indicates that user is not authenticated due to absence of valid credentials
+	Unauthenticated Type = 10
 )
 
 // Type is a type of the Error