Don't auto-install, add aquameta --init command-line option

[erichanson]

It's cool that Aquameta installs itself, but this shouldn't be done automatically. Instead, if the daemon's check that Aquameta is installed on a database fails, it should prompt the user:

./aquameta -c conf/boot.toml
Aquameta is not installed on this database.  To initialize the database, use --init.

# oh ok
./aquameta --init -c conf/boot.toml