Bring in udev & libdevattr

Bring in udev & libdevattr

* Bring in kern_udev, libdevattr and udevd from my personal repo. This
  is still WIP, but basic functionality is available and the API is
  stabilizing.

* kern_udev allows the association of certain parameters in form of a
  dictionary to each device in the system and provides notification of
  attach and detach events.

* udevd is a userland daemon which keeps an up to date list of all
  devices and their dictionaries and provides an interface for
  libdevattr to acccess and manipulate these devices and related events.

* libdevattr provides a mostly Linux' libudev compatible API to access
  device dictionaries and events. Beware that it is NOT a full drop-in
  replacement!