vis: Convert to procd based init script

The legacy init script had various problems in comparison with procd based
init scripts. It wasn't able to correctly track the running process
instance and thus could:

* accidentally kill another (non init controlled) daemon instance when stop
  is used
* not restart the daemon depending on config changes when reload is used
* not automatically start/restart daemon when the used netdev was
  created/recreated

The information about a running instance and its parameters can now be
handled by a global controller (procd). The process must not fork anymore
and leave the control to procd. The process with its parameters can then be
used by procd to trigger the stop/start of the process at the right time.

Signed-off-by: Sven Eckelmann <sven@narfation.org>