Improvement to age restrictions

Age restrictions are based upon the age of the child at the season registration date but this causes some issues. 

If class start date is way beyond the season start date then the system incorrectly restricts the registration by the public user and this leads to confusion and call to our facility.

Having an age restriction based on the actual class start date would solve the problem. Could use a hierarchical approach to make this very flexible, Look for age restrictions on class then on level, then on season