xmpp: audit exception handling

[jahschwa]

Example of missed exception:

2018-10-31 03:13:05 | xmpp     | DEB | Got presence: sibyl@conference.example.com/Sibyl (type: unavailable, show:
 None, status: None, subscription: none)
2018-10-31 03:13:05 | xmpp     | ERR | Forced from room "sibyl@conference.example.com" (shutdown)
2018-10-31 03:13:05 | xmpp     | DEB | Rejoining room "sibyl@conference.example.com" in 60 sec
2018-10-31 03:13:05 | sibylbot | CRI | UNHANDLED: SystemShutdown

Traceback (most recent call last):
  File "/usr/src/app/sibyl/lib/sibylbot.py", line 1186, in run_forever
    self.__run_forever()
  File "/usr/src/app/sibyl/lib/sibylbot.py", line 1065, in __run_forever
    self.__serve()
  File "/usr/src/app/sibyl/lib/sibylbot.py", line 1041, in __serve
    proto.process()
  File "protocols/sibyl_xmpp.py", line 295, in process
    self.__idle_proc()
  File "protocols/sibyl_xmpp.py", line 745, in __idle_proc
    self.__idle_ping()
  File "protocols/sibyl_xmpp.py", line 762, in __idle_ping
    self.opt('xmpp.ping_timeout'))
  File "/usr/src/app/xmpp/dispatcher.py", line 337, in SendAndWaitForResponse
    return self.WaitForResponse(self.send(stanza),timeout)
  File "/usr/src/app/xmpp/dispatcher.py", line 321, in WaitForResponse
    if not self.Process(0.04):
  File "/usr/src/app/xmpp/dispatcher.py", line 303, in dispatch
    handler['func'](session,stanza)
  File "/usr/src/app/xmpp/dispatcher.py", line 215, in streamErrorHandler
    raise exc((name,text))
SystemShutdown: (u'system-shutdown', u'Received SIGTERM')

2018-10-31 03:13:05 | sibylbot | CRI | Please consider reporting the above error to the developers.