Explicit thumbnails nicer to look at

[RalekArts]

Remove placeholder from Explicit thumbnails and replace with brighter warning sign, see:Derpibooru for example. For slower end users, possibly also add a text warning in the form of a red E to the left of the title. Simple, but lets users who's images haven't loaded yet from clicking on one accidentally.

[Csardelacal]

I added the red (E) to the explicit auctions. Also rearranged the layout of the title a little so the card doesn't look so crammed.

Also, would need a suggestion for that explicit image.