AssociationTableMixinClassReflectionExtension must rely on generic to detect native methods

[rochamarcelo]

Related to #55

[rochamarcelo]

@dereuromark Could you test this. Now it should not cause errors when using annotation

@property \Cake\ORM\Association\BelongsTo<\App\Model\Table\UsersTable> $Users

$this->Notes->Users->findByNamed('John Doe')->id// Native method to return User

$this->Notes->Users->findByRole('admin')->all()->toArray()//Magic finder method (not native method)

[dereuromark]

Works great!