Multiple accounts/additional accounts

I'd like to be able to add multiple Twitter accounts to my Keybase account. Additionally, I'd like to be able to add other social accounts. I know it's completely one-off, but it would be amazing if I could add my Tent account (Tent users really, really like your service). Whether this be through a method where I make a generic public post (there could be different types; for example, microblogging, image, long-form, etc. that we can choose from) or a specific auth/identification method doesn't matter.

No files, tests, or entry points are identified in this request. Before implementation, clarify the supported account types and verification method; completion would require an agreed design for multiple Twitter and other social accounts, including Tent.

Written by the indexing model from the issue text.