Don't require UIDs to be 36 characters

The spec strongly recommends this, but doesn't strictly require it

creditcards.go

@@ -21,9 +21,7 @@ func (r *CCStatementRequest) Name() string {
 }
 
 func (r *CCStatementRequest) Valid() (bool, error) {
-	if ok, err := r.TrnUID.Valid(); !ok {
-		return false, err
-	}
+	// TODO implement
 	return true, nil
 }