Inteligent Date Widget

I have added a new date widget, "FutureDate", which will highlight if the selected date is in the past or invalid.

It also gives a hint to the date format if you have javascript disabled, as otherwise it'll be a real pain to use.

So far I've only added it to the auditions pages, but it should be useable throughout - I think in most cases, we'd expect dates entered to be in the future, and this helps the user ensure that's the case (while also allowing them to enter past dates for e.g. shows in the past).