Bug: CLI exc handling needs to consider network issues

[jamoore]

Similar to all of the issues Jean-marie has recently been handling in insight, the CLI client will also need error handling for catching server-restarts and similar.

Here is a stack trace from a Ctrl-C of a delete after the server was restarted:

.(ome1)jamoore@blue:/opt/ome2$ dist/bin/omero delete /Plate:101
Previous session expired for root on localhost:4064
Server: [localhost]
Username: [root]
Password:
Created session fb41b384-a1a7-45f9-a27c-ac73f342be85 (root@localhost:4064). Idle timeout: 10.0 min. Current group: private

^CAttempting cancel...
Traceback (most recent call last):
  File "dist/bin/omero", line 125, in <module>
    rv = omero.cli.argv()
  File "/opt/ome2/dist/lib/python/omero/cli.py", line 1195, in argv
    cli.invoke(args[1:])
  File "/opt/ome2/dist/lib/python/omero/cli.py", line 745, in invoke
    stop = self.onecmd(line, previous_args)
  File "/opt/ome2/dist/lib/python/omero/cli.py", line 814, in onecmd
    self.execute(line, previous_args)
  File "/opt/ome2/dist/lib/python/omero/cli.py", line 894, in execute
    args.func(args)
  File "/opt/ome2/dist/lib/python/omero/cli.py", line 1438, in main_method
    self._process_request(req, args, client)
  File "/opt/ome2/dist/lib/python/omero/cli.py", line 1284, in _process_request
    rsp, status, cb = self.response(client, req, wait = args.wait)
  File "/opt/ome2/dist/lib/python/omero/cli.py", line 1362, in response
    if handle.cancel():
  File "/opt/ome2/dist/lib/python/omero_cmd_API_ice.py", line 708, in cancel
    return _M_omero.cmd.Handle._op_cancel.invoke(self, ((), _ctx))
Ice.UnknownLocalException: exception ::Ice::UnknownLocalException
{
    unknown = Network.cpp:1243: Ice::ConnectionRefusedException:
connection refused: Connection refused
}

[jburel]

Something to consider since CLI tool is getting used more and more