OSError if deluged not installed and attempted start from connection manager

[Cas]

Start in non-classic and try to start daemon from connection manager. The correct warning appears in gtkui but error is not handled properly.

[ERROR   ] 18:14:58 client:584 [Errno 2] No such file or directory
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/deluge/ui/client.py", line 582, in start_daemon
    subprocess.call(["deluged", "--port=%s" % port, "--config=%s" % config])
  File "/usr/lib/python2.7/subprocess.py", line 493, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/usr/lib/python2.7/subprocess.py", line 679, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1239, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory

[Cas]

​eb6959fb