Disabled Images in Signatures

[radare]

I'm disabling the use of Images in the signatures. Several have started adding animated GIFs to their signatures and I find it wholly distracting from the sites content. Since I can disable GIF images specifically, I'll have to disable all of them.

This change is not retroactive, meaning that if you already have an image in your signature, it'll still be there. This will just apply to those trying to add one in the future.