Better server maintenance tools

[NfNitLoop]

As a server admin, I should be able to use the CLI to:

• [x] See how much data users are using.
• [ ] Delete and/or ban particular content/users I find objectionable.
• [x] Delete data that is no longer used. (ex: users that are no longer followed)
• [ ] Find out why a particular user/Item is on my server. (Who follows this person?)

In the meantime you have to make DB calls yourself.

[NfNitLoop]

These two are going into v0.6.0:

See how much data users are using

See the db usage subcommand.

Delete data that is no longer used. (ex: users that are no longer followed)

See the db prune command.