implement record add/remove for route53

[codefromthecrypt]

Here's code to add a record to a set.

ResourceRecordSet toAdd = ResourceRecordSet.builder().name("www.denominator.io.").type("A").add("1.1.1.1").build();
Change creating = resourceRecordSetApi.create(toAdd);

// replace below with your favorite polling loop, or.. just let it ride
checkState(Predicates2.retry(new Predicate<Change>() {
         public boolean apply(Change input) {
            return route53Api.getChange(input.getId()).getStatus() == INSYNC;
         }
      }, 600, 1, 5, SECONDS).apply(creating), "%s never synced!", creating);

same process to remove, except s/resourceRecordSetApi.create/resourceRecordSetApi.delete, and you could get a null change if the record was already removed.