VdsClient command should provide more debug information

Issue

• When the vdsClient command fails it gives little information on why it fails (e.g. if it has an issue with a vm):

[root@lab ~]#  vdsClient -s 0 list table

Traceback (most recent call last):
  File "/usr/share/vdsm/vdsClient.py", line 2411, in <module>
    code, message = commands[command][0](commandArgs)
  File "/usr/share/vdsm/vdsClient.py", line 280, in do_list
    response = self.s.getAllVmStats()
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1199, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1489, in __request
    verbose=self.__verbose
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1253, in request
    return self._parse_response(h.getfile(), sock)
  File "/usr/lib64/python2.6/xmlrpclib.py", line 1387, in _parse_response
    p.feed(response)
  File "/usr/lib64/python2.6/xmlrpclib.py", line 601, in feed
    self._parser.Parse(data, 0)
ExpatError: not well-formed (invalid token): line

Version-Release number of selected component (if applicable):

• Request for Enhancement: Either the command runs per client and outputs the result and/or provide an error indicating which vm is the cause of the issue.