Allow sub-classes access to Services

Here's my dilemma: I want to use a different REST Client for the services, but because they are private, I would otherwise need to copy all the methods into my subclass in order to override the ConstantContact REST client. This way, I can do the following:

`
class KWSConstantContact extends ConstantContact {
	public function __construct($apiKey) {
		parent::__construct($apiKey);
		$this->setRestClient(new CustomRestClient());
	}
}
`

If there's a better way I don't know about, please let me know. Allowing sub-classes access seems like an easy way to add lots of flexibility without much risk.
Merge pull request #3 from katzwebservices/patch-2

Allow sub-classes access to Services