Manpages

See pump-io/pump.io#1200:

- [ ] `pump-authorize(1)`
- [ ] `pump-create-group(1)`
- [ ] `pump-delete(1)`
- [ ] `pump-follow(1)`
- [ ] `pump-post-file(1)`
- [ ] `pump-post-note(1)`
- [ ] `pump-register-app(1)`
- [ ] `pump-register-user(1)`
- [ ] `pump-set-password(1)`
- [ ] `pump-show-group-inbox(1)`
- [ ] `pump-show-inbox(1)`
- [ ] `pump-show-outbox(1)`
- [ ] `pump-stop-following(1)`