Removed some older/unused API versions for four different services.
DRY'd code that had to be done for each service.

* Registering autoloads for service interfaces
* Adding service helper methods to Region
Translated README from rdoc to markdown, restructured content.
Added additional rake tasks for updating docs.

The API documentation contains lists of supported
services and service classes.  A pair of rake tasks
have been added that will update these lists when
docs are built to ensure they do not get stale.
Updated README examples.
Added service shortcuts from AWS.

You can now create service interfaces directly from AWS like so:

    ec2 = AWS.ec2

You can pass configuration options to this instance as well:

    ec2 = AWS.ec2(:region => 'us-west-2')

Updated docs rake task to document these magic methods.
Fixed a few test issues with the new service shortcuts.