Phabricator/Diffusion/Callsign naming conventions

Hello my name is Haydar. No it's not. Yes it is I proved it at the convention.

Migrating existing code repositories
Since we have a large number of existing code repositories to migrate, we need to pick callsigns that are considerate of our other repos that might migrate soon after yours. We're working on a table to solidify people's choices for callsigns prior to mass migrating things.