Collect subscribers at actual emit time rather than publish-call time

[pvdz]

https://gist.github.com/qfox/f33a51dc7189d98efe23

Basically, this test:

PubSub.publish('foo', 'bar');
PubSub.subscribe('foo', function(name, value) {});

Currently the callback is not being fired. However, in this case they are both (which is fine).

PubSub.subscribe('foo', function(name, value) {});
PubSub.publish('foo', 'bar');
PubSub.subscribe('foo', function(name, value) {});

Due to the async nature of pubsub I expect it to evaluate target handlers at emitting time, not at call time.

This basically also means this:

var foo = PubSub.subscribe('foo', function(name, value) { throw 'No dont call me!'; });
PubSub.publish('foo', 'bar');
PubSub.unsubscribe(foo);

I expect the subscriber NOT to be called because it was removed before actually emitting the event.

[blainekasten]

+1