Add support of query pagination with WillPaginate

Hi.

There's my contribution! Can you check that please?

How can we made tests for this integration?

Thanks a lot
Hi! Thanks a lot for your review! :)
I have used per_page as a method because when its called it sets the limit of chewy query.

```ruby
+        def per_page(value = :non_given)
+          if value == :non_given
+            @per_page
+          else
+            @per_page = value
+            limit(value)
+          end
+        end
```

maybe I should define everything on paginate method?