Optional bounds for full count

[ianmacartney]

If I want to get the full count, I'd like to just do:

aggregate.count(ctx);
// instead of 
aggregate.count(ctx, {bounds: {}});

And for a namespace I'd like to do:

aggregate.count(ctx, { namespace: userId });

setting bounds to {} is not super discoverable, I assumed I needed to specify prefix or something.