Setup should look at existing range indexes

[hunterhacker]

Geert writes: "Oh by the way, there already is a bit of admin interface. I think you could get more out of this setup wizard. Why doesn't it auto-detect present indexes, and suggest to add them as facets?"

Ryan writes: "I think that's a great suggestion for an enhancement to the setup page. We could easily grab a list of range indexes that exist but aren't configured under Corona and ask the user to assign names to them and configure their buckets if they so desire."