vol AttachByName should mimic other volpkg errors

vol AttachByName should mimic other volpkg errors

if later callers will deem a volume offline, note it at attach time.
additionally, log the cause.

(cherry picked from commit 939382c5c1622750665a9f543168bd3b8044583f)

Change-Id: Ie5d4a6339749c4f1920a78722966b013e78ffd98
Reviewed-on: http://gerrit.openafs.org/2465
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jason Edgecombe <jason@rampaginggeek.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jason Edgecombe <jason@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit fd19dd095a52be4a685ac80e8533b7a4388e145c)