add a way to select the per-guild avatar or the global avatar

[onerandomusername]

There's not a good way to view which avatar you want to view. I propose either a subcommand or a new command to explicitly choose. The current one does the display avatar, so a subcommand might be more beneficial. Of course, adding a subcommand for the per-server avatar would be nice too, in case someone has the same name as the subcommand.

[Run1e]

#69 nice