Give clickable props a "pointer" cursor AGAIN

So we removed the cursor attribute of "clickables" at some point...

And now they're called props. They're not ALL clickable now! I've added some logic to wall.js that checks that either there is an 'action' defined for the prop, or there is a 'hoverImage' defined. Only then will the cursor change. If no 'hoverImage' is defined, then the cursor change is applied to the normal prop image.