Kill some old, unnecessary require statements.

More than one result is very rare and it's not clear how one would
evaluate the choices. If this is required in the future a new method
can be added.

This fixes a scope problem: blocks are evaluated in the context in which
they are declared so custom routines were being evaluated in the context
of the class, not the object.

Don't take 'reverse' argument, instead figure it out by looking at what
options were specified for the model. Also, don't raise exceptions on
bad configuration (no longer possible to detect, wasn't that important).

city, country, country_code, postal_code

Should have been part of commit 29af848a.

Split result parsing into separate method.

No longer necessary.

Use JSON (json gem) instead.

Move model class methods to separate module.

Add Geocoder::Orm::Base module.

For advanced/custom handling of gecoding result data.

This is a generic method for fetching geo data and storing it in the
object (now used by fetch_coordinates and fetch_address).

Instead detect further up the chain (before calling the Lookup).

Geocoder.search now always returns an array. Thanks to
github.com/infinityrobot for reporting the bug.

Prefer to rely on lower level methods (reduce dependencies).

Also move 'address' and 'coordinates' methods from Geocoder::Lookup::Base
to Geocoder. This simplifies the interface and allows us to choose a
lookup engine dynamically for other types of geocoding (eg: IP addresses).

Prepare to add support for Yahoo in addition to Google.

Add implementation for Google and anticipate addition of Yahoo (supply
config option).