Support images in Avatar

[gabro]

Avatar should accept an optional imageSrc prop.

It would be cool if we could show the default icon (or initial, depending on whether username is set or not) while the image is loading or if the image fails loading (possibly because the url is wrong or unreachable)

I think it may be achievable by using an <object> tag and nesting the fallback in it, but I haven't explored it much