Fetch api values

[giosce]

I'm working on adopting public code by a large US organization. We will need more changes, this is a basic one. My ideal approach is to have as much common code as possible and have country or organization customizations as much as possible in config files.

This change allows to populate the "Scope" dropdown from a different source, in this case from our Taxonomy API. It is backward compatible, if someone doesn't provide a fetch URL the app will continue to work like it is now.

Happy to review/discuss this and other change ideas.