civicrm_option_value.value is text, so can't use MAX()

So this field is text, not an integer, so if we SELECT MAX(value) we get incorrect results if the highest value is > 9. We either need to use SELECT MAX(ROUND(value)), or change the field to be an integer.

This issue exists in the upgrade php script and sql script. I'm guessing it might occur in other places in core as well.