Fixed `Include` Bug

Hi.

I fixed the error with `include` method.

Before 

```ruby
   module M
     def a
       'M:a'
     end
   end

   class A
     include M
     def a
       'A:a'
     end
   end 
   #and
  class B
    def a
      'B:a'
    end
    include M
  end

  A.new.a #=> 'A:a' - ok
  #but
  B.new.a #=> 'M:a' - wrong
```
Also i change `Native` from `module` to `class`. 

Thanks,