Code review for services/

Pretty sure I'm doing this wrong @zzmp, but here's the files I'd like you to review.
A big reason for the closures in this section is that the async library restricts what arguments are passed into it's callback and wanted access to more. For example, in order to filter properly within isNewMembers, I needed access to the members already in the org. I couldn't think of a way to make these pure functions so I just put them inside closure. Is styling the only consideration here? Is there a better way I could do this?