Artist portraits implemented

[Gigablah]

Staff may now upload portraits for artist profiles (accessible through the artist editing page). It functions very much like the scan management page. Currently the profile page will display the image that's set to default. I'll think of a mechanism to scroll through different portrait images.

Also, all portrait images are automatically sized to 100 pixels in width. The filesize limit is set to 2 megs, that should be more than enough.