Added OOP class

I've added a OOP version of the hbattat's script. It works this way:

1. Create a new EmailVerifier instance assignating as params the email
to test and the email that will be used as source. Ex:

$verifier = new EmailVerifier('test@domain.com', 'source@domain.com');

2. Use validate() for get the result of the testing. It'll be returned
as an array with the status and the details of the testing.

Bugs and feedback, feel free to send them to me :)
Peace !!!