Fix date

I believe this will fix the problem Fox is having, but since I can't replicate it I don't know for sure.

Previously, it's theoretically possible that an object could pass through this method unscathed if it didn't match any of the regexes. That's exceedingly unlikely if the object was a Date, but if another kind of object is getting passed in, that could be the problem. I can't find anyplace that does this, though.

I'll be patching this change into the old version of photo-wall (3), and once it gets accepted here into the new version as well.