Lets make it larger then!

The avatar URL generation code is at https://github.com/mozilla/login.webmaker.org/blob/master/app/models/user/sqlModel.js#L105-L112 ; We could just increase the basic size from 26x26 to something larger, or we could remove the size key from the URL so that anyone using the URL can append their own size key (400 in this case I guess?)

If we're using a 400x400 avatar, we'll also need to increase the size of the default webmaker avatar stored on stuff.webmaker.org.