Allow collections of editors

This is dependent on being able to search for edits related to a collection (SEARCH-463).

I'd love to be able to make collections of editors and then search for edits by editors within one collection. E.g. I'd have a collection of editors who are very reasonable with their recording-merges, one collection of new editors I want to keep a watchful eye on and maybe a collection of bot-editors just to name a few.