extract volatiles for at into own bbappend
Update nginx bbappend for /var/lib move

* when bind-mount /var/lib instead of union-fs, /var/lib/nginx must exists
  before nginx is started
* rename bbappend file to be save on upgrades
acquire /var/lib r/w access via mount-bind instead

depreciate union-fs for /var/lib
move hp2 user into dedicated recipe

including correct volatiles settings for logging
on update, wipe out .var_lib
add helper for hard-reseting files in r/w of union

Because of the nature of the beast, you can't unlink files in the underlying
r/w filesystem of a unionfs. In rare cases where starting fresh is a viable
case, system reset is required and a list of file system entries to be
removed must be processed before unionfs is mounted.

Misuse can damage your file systems and lead to continuous kernel panics.
Use with caution!
rename at bb to bbappend
add missing license for hp2-base