Update for MySQL timezone detection bug

Use "DefaultTimeLoc" for "al.TZ" default value
Don't set TZ on alias when t.Location() is empty

You can set your MySQL server timezone on main.go init function.
Example :
orm.DefaultTimeLoc, _ = time.LoadLocation("Europe/Paris")

orm/db_alias.go

@@ -119,7 +119,7 @@ type alias struct {
 func detectTZ(al *alias) {
 	// orm timezone system match database
 	// default use Local
-	al.TZ = time.Local
+	al.TZ = DefaultTimeLoc
 
 	if al.DriverName == "sphinx" {
 		return
@@ -136,7 +136,9 @@ func detectTZ(al *alias) {
 			}
 			t, err := time.Parse("-07:00:00", tz)
 			if err == nil {
-				al.TZ = t.Location()
+				if t.Location().String() != "" {
+					al.TZ = t.Location()
+				}
 			} else {
 				DebugLog.Printf("Detect DB timezone: %s %s\n", tz, err.Error())
 			}