Print a list of stanzas if an error.
Added logging into escalus_bosh.
Made escalus_bosh:stop/1 blocking.
Allow to pass atom as a username to escalus_event:new_client/3.
Handle an undefined resource (escalus_event).
Dumping history into a XML file.
New tags: story_start and story_end.
Patched escalus_ws. Pass all outgoing_stanzas to escalus_event.