Subscribing to changes from the store doesn't always play nice with hot-reloading

[mvestergaard]

When using something like Rx observables to subscribe to changes in the store, it appears that hot-reloading can sometimes cause the subscriptions to be hooked up again, which can cause duplicate events.

[gaearon]

Yeah good point. Need to figure this out before shipping 1.0.

[gaearon]

Meh, this won't fit into 1.0.
Let's consolidate this with similar issues in #350.

[gaearon]

Now we encourage people to use hot module replacement API directly, so that you have full control: #667