When dissecting an NFS file handle, show the raw bytes of the file

When dissecting an NFS file handle, show the raw bytes of the file
handle data (snoop does this, and it's somewhat convenient if you're
trying to see whether, say, an ACCESS call is acting on the file whose
file handle you got back from a previous MOUNT request).

Boost the maximum number of bytes worth of hex data shown by
"bytes_to_str()" from 10 to 16, so that we can show the file handle 16
bytes per line (as snoop does).

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@1744 f5534014-38df-0310-8fa8-9805f1628bb7