[L4] Checkbox checked state does not get set properly

The checkbox state was not set correctly, they were always checked. (I am using L4 with MySQL, in my DB unchecked value is 0 with boolean type).

Changing the configuration unchecked_value to '0' from 0 and it sorted out my problem. Looks like there are some previous problems with checboxes, maybe it will relate with some other problems eventhough the solution is simple.