install AFSCommander in prefpane dir

install AFSCommander in prefpane dir

make the AFSCommander prefPane be installed, in /Library (as
are growl, macfuse, etc)

Reviewed-on: http://gerrit.openafs.org/243
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 6640b8b064b238333a46ef72aa09913b06271a91)
Change-Id: Ic9e46c62ee3587012bed33c737573cfc18b4672d
Reviewed-on: http://gerrit.openafs.org/946