dh_installudev transition

dh_installudev transition

* dh_installudev: Install rules files into new location
  /lib/udev/rules.d/
* dh_installudev: Add code to delete old conffiles unless
  they're modified, and in that case, rename them to override
  the corresponding file in /lib/udev. (Based on patch by
  Martin Pitt.) (Note that this file will not be deleted on purge --
  I can't see a good way to determine when it's appropriate to do
  that.)
* dh_installudev: Set default priority to 60; dropping the "z".
  If --priority=zNN is passed, treat that as priority NN.
* Above Closes: #491117
* dh_installudev: Drop code handling move of /etc/udev/foo into
  /etc/udev/rules.d/.