Handle error stanzas properly

For example, when an user gets ghosted (it’s gone but nobody told that to biboumi) and biboumi sends messages to it, we receive an error message in response. At the moment biboumi interprets it as a normal message, that’s bad.

We should kick any JID that returns errors to us. Maybe take inspiration from http://hg.prosody.im/trunk/file/7a8899d314d7/plugins/muc/muc.lib.lua#l46

And by kick, it’s not enough to remove it from the channel that generated the message in the first place, we should destroy the whole Bridge object, along with all the IrcClient children (so, all connected channels of every servers).

(from redmine: created on 2014-05-08, closed on 2014-05-14)