Add path redaction to distupgrade plugin

The preupgrade-assistant package stores listings of user home
directory content in /var/cache/preupgrade/allmyfiles.log:

  [...]
  /etc/yum/vars
  /etc/yum/version-groups.conf
  /home
  /home/bmr
  /home/bmr/.bash_logout
  /home/bmr/.bash_profile
  /home/bmr/.bashrc
  /home/bmr/.cache
  /home/bmr/.cache/event-sound-cache.tdb.5a13c21f03268e5eedd52b3000000017.x86_64-redhat-linux-gnu
  /home/bmr/.config
  /home/bmr/.config/gnome-disk-utility
  [...]

Since file and directory names in these locations could be
considered sensitive by some users redact all paths beneath /home
in this file:

  [...]
  /etc/yum/vars
  /etc/yum/version-groups.conf
  /home
  /home/******** path redacted ********
  /home/******** path redacted ********
  [...]

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>