changing `url` config to `host` and `port` configs

Separating these out to match up with AR's configs.  URL doesn't
actually affect AR.
configure active record with defined `db_settings`

The config should take its db configs and produce a string-keyed
hash of the non-nil settings.  This value will be used to configure
active record.

The goal here is to lock down and configure active record more
closely to how a database.yml would.  This should prevent cryptic
connection failures b/c of bad connection settings.
cleanup: rename init control var for establishing AR connections

Just trying to be clear on what the variable controls.
have the connect command actually get a connection from the pool

This is a better test that everything connected properly.
Merge pull request #33 from redding/kr-moreusage

Fixes to connecting to remote databases