Fix Valid Toggle

Fix `validToggler()` to correctly toggle on Expiry Date. Seems like
`jquery.payment` couldn't work with formatted date, as parsed by `val`.
I might be stupid, but this is the only way I got it to run.
I have cleaned it up as much as I can. I don't want to put the logic inside the returned method, as then the logic will be run over and over, instead just once.