Embedded classes reflection new instance creation with internal PHP classes

@deeky666 @Ocramius @stof,

This broke any embeddable that extends an abstract class.  That's because if a property is defined in the abstract class, <code>$this->class</code> is alway the abstract class and thus cannot be instantiated.  The <code>$class</code> parameter that is passed into the constructor needs to be stored, and that class should be instantiated, not the the property's declaring class.  I will write up an issue and pull request to address this.