Use person.name instead of personal, middle, and family names

Fixes #61.

I haven't touched `db.sql`, because it seems to be auto-generated from
secret data (`make import`).  I haven't touched `migrater.py` either,
since I'm not sure how to handle schema migrations in that script.
Rather than manipulating `db.sqlite3`, it seems like it would be
easier to just have a script that went through `roster.db` and spit
out SQL directly.  Anyhow, something that someone with access to
`roster.db` and an understanding of `migrater.py` to handle ;).