repaired placeholders {minLength} and {maxLength} to {0} in lexicons

Repaired placeholders {minLength} and {maxLength} which aren't replaced by values. See bug on screenshot.

![modx chyba - maximln dlka pole url alias](https://cloud.githubusercontent.com/assets/1145071/3487198/d8210128-046b-11e4-92bb-4053cb43704f.png)