Async Refactor: query functions are now async functions

[kumavis]

This refactor changes the queryFns to be async. The makePath functions are still synchronous

const q = new Query(dht, peer.id.id, () => {
  // makePath: do once-per-path setup
  return async () => {
    // queryFn: do actual query
  }
})

No behavioral changes were intended, but some tests needed timeouts added to their query functions in order to resolve as expected

related #82

[vasco-santos]

Thanks for the PR @kumavis

It looks good and I only notice some minor details

[vasco-santos]

LGTM!