Added option to allow retention of partially filled in masked fields

Updated Cakefile so it would not complain about out of support stuff, added a test in Focus.Spec.js and then added feature to masked method to allow the passing in of a new option, retainPartial. This should allow for better integration with the jquery validate library, as previously on partially entered data, the field would clear before jQuery Validate had a chance to even test the field's partial value for any sort of correctness.

Basically, we have fields that have remote validation rules, and they are masked. If the person left the field before the mask was fully filled in, it cleared it, never gave a chance for our remote validation rules to do anything interesting! This should hopefully fix it!