Clarification: Index.to_native_types() always converts to strings
This may have been intended, but this change (https://github.com/pydata/pandas/commit/3d54482bbd8086c27a01d489a0ae751e0b9c3731) released in 0.16.2 broke some of my code because `Index.to_native_types()` started converting all index types to strings, even integers. By reading the source I found I can prevent that by passing `quoting=True` to `to_native_types`, but since there's no documentation for `to_native_types` I wanted to get a little clarification: What is the expected behavior of `to_native_types` and what does the `quoting` keyword mean? Thanks!
