(logging) minor adjustments to error-level logging (@author arossi)

I have gone through all the .java files carrying the annotation @author arossi, looking for logging irregularities.  I have tried to eliminate things like logger.error logging a stack trace when not clearly an unexpected exception (bug).  There are also a few other minor fixes.

Target: master
Patch: http://rb.dcache.org/r/5690/
Require-notes: no
Require-book: no
Acked-by: Paul