kill apsl afssettings and fstab

kill apsl afssettings and fstab

replace both

afssettings with something patterned from webdav's (BSD-licensed)
mount program with general plist reading code. the lists of
valid oid objects of course have to be the same. eject old
darwins. add the new one.

fstab with something from freebsd umount

Change-Id: I28f6765475314b9b78102c762daec19cda4988c3
Reviewed-on: http://gerrit.openafs.org/1583
Reviewed-by: Russ Allbery <rra@stanford.edu>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>