Add service specific options to AWS.config

You can now specify a service endpoint, region or port via AWS.config without using the deprecated prefixed versions.

    # new format
    AWS.config(:s3 => { :region => 'us-west-2' })

    # deprecated
    AWS.config(:s3_region => 'us-west-2')

This could eventually be expanded to support other configuration options (e.g. `:logger`, `:max_retries`, etc).  Please note, the top level configuration options for AWS::SimpleWorkflow and AWS::SimpleEmailService use a new short-name.  Previously, these services used the short names, `:simple_email_service` and `:simple_workflow`.  These prefixes are now deprecated, and you should now use the `:ses` and `:swf` prefixes.

    # deprecated, but still works
    AWS.config(:simple_workflow_region => 'us-west-1')

    # new format
    AWS.config(:swf => { :region => 'us-west-1' })

Additionally, the helper methods on `AWS` and `AWS::Core::Region` have been renamed to use the new short names.

    # deprecated
    AWS.simple_email_service
    AWS.simple_workflow
    AWS.regions['us-west-1'].simple_workflow

    # new format
    AWS.ses
    AWS.swf
    AWS.regions['us-west-1'].swf

As part of the refactor, the documentation rake tasks had to be udpated to reflect the new helpers.  Additionally, the internal AWS::SERVICES constant how uses a helpful utility class to manage the aliases for the renamed helpers and options.