afscp: Always show fetch/store errors

afscp: Always show fetch/store errors

When we get an error from a fetch or store operation, show what the
error was, instead of just saying "some network error occured".

Change-Id: I4b1baca0e1b11bd048014ef2b4f4789c7813f0e7
Reviewed-on: http://gerrit.openafs.org/3290
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>