Handle broker outage

[xitep]

kafka-rust currently does a poor job of handling errors. It basically pushes all the responsibility to client code. However, that client code's only option, is to reload metadata and to try the operation again. There are various situations, though, where kafka-rust can do much better.

In particular - in the scope of this ticket - we'd like Producer and Consumer to try to "survive" the outage of a particular kafka broker in a cluster. In other words, the two clients shall transparently deal with partition leader re-assignment and temporary kafka errors.

More details to come.

[thijsc]

Any progress on this one?

[xitep]

unfortunately, no. not that i'm aware of. feel free to tackle this one. my focus is currently rather on #63.