Fix of the following error on stop:

er at 0x7f3c7a523a10>
Traceback (most recent call last):
  File "/home/giampaolo/svn/samsung/cellar/.venv/bin/zdaemon", line 9,
in <module>
    load_entry_point('zdaemon==4.0.1dev', 'console_scripts',
'zdaemon')()
  File
"/home/giampaolo/svn/samsung/cellar/.venv/src/zdaemon/src/zdaemon/zdctl.py",
line 615, in main
    return zdaemon.zdrun.main(args)
  File
"/home/giampaolo/svn/samsung/cellar/.venv/src/zdaemon/src/zdaemon/zdrun.py",
line 708, in main
    d.main(args)
  File
"/home/giampaolo/svn/samsung/cellar/.venv/src/zdaemon/src/zdaemon/zdrun.py",
line 226, in main
    self.run()
  File
"/home/giampaolo/svn/samsung/cellar/.venv/src/zdaemon/src/zdaemon/zdrun.py",
line 235, in run
    self.runforever()
  File
"/home/giampaolo/svn/samsung/cellar/.venv/src/zdaemon/src/zdaemon/zdrun.py",
line 411, in runforever
    self.dorecv()
  File
"/home/giampaolo/svn/samsung/cellar/.venv/src/zdaemon/src/zdaemon/zdrun.py",
line 492, in dorecv
    self.docommand()
  File
"/home/giampaolo/svn/samsung/cellar/.venv/src/zdaemon/src/zdaemon/zdrun.py",
line 510, in docommand
    method([a.decode() for a in args])
  File
"/home/giampaolo/svn/samsung/cellar/.venv/src/zdaemon/src/zdaemon/zdrun.py",
line 547, in cmd_restart
    self.delay = time.time() + self.options.stoptimeut
TypeError: unsupported operand type(s) for +: 'float' and 'NoneType'