app(logger): restore the old behaviour

that is - have the Logger() method return pointer to the local (s)logger

app/app.go

@@ -84,7 +84,7 @@ func (a *App) E() *echo.Echo {
 
 // Logger returns app's pointer to the global logger instance.
 func (a *App) Logger() *slogging.Logger {
-	return a.slogger
+	return &a.logger
 }
 
 // PrintConfiguration outputs relevant settings of the application to console.