Logos/profile pictures

[tkuhn]

Users and projects should be able to specify their logos/profile pictures.

[ashleycaselli]

A User can now specify their profile picture using this template: https://w3id.org/np/RAV6PgoKtIc5pkI0AXRbmwRlTFpA-DHytaZfEFGq3OTjo

The profile picture must be a publicly accessible URL (e.g., one's GitHub profile picture; https://avatars.githubusercontent.com/u/28731055)

[tkuhn]

Nice! :)

Can we use the same mechansism also for #226?