Merged the code into to v4 and v5 of Elliot's ACF Field Type Template

Hi Will,

Thank you for this field, it's been really useful. I thought I'd help and merge this into [Elliot's field type template](https://github.com/elliotcondon/acf-field-type-template) so it's now compatible with both ACF version 4 & ACF v5 (ACF Pro). It works as a standalone plugin or via the standard include method.

Cheers,

Stef