This fixes issue #260.

This addresses issue #199 and is more directly a response to the
excellent comments from github.com/zetetic on commit 1b658304.

This change will call the writer methods defined on an AR model, if they're
implemented, instead of going behind their back. This also avoids a rails 3
deprecation warning, if the named attributes aren't actually database
attributes.

it is better and faster

Fixes bug in -j and -u options.

Fixes: #194 - add_exclude_condition breaks on tables without ID field - https://github.com/alexreisner/geocoder/issues/194

Also rename :ignore to :geo_only (more descriptive/specific--we might
introduce other options in the future and :ignore is kind of vague).

in request to geocoding service.

Also move some lookup-related methods to Geocoder::Lookup module.

This is in preparation for adding Maxmind as an IP lookup.

Thanks github.com/johanneswuerbach.

Thanks github.com/johanneswuerbach.