doc: generate admin ref from the pod documentation

doc: generate admin ref from the pod documentation

a bit convoluted but this generates docbook from the pod documentation and
from that pdf, epub and mobi versions.  we are using variablelist.as.block
since that looks prettier on smaller devices/screen.

Change-Id: I5cd51ef10448373960a0aeed15212bbcf6f44039
Change-Id: Ib222dbfa30e3af644b1dbc6738df1d39cc33c92f
Reviewed-on: http://gerrit.openafs.org/5255
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>