gssd: Use italics for option values and pathnames

Clean up: The usual convention for the values of command line
options and for pathnames is for them to appear italicized,
rather than emboldened or in double quotes.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Steve Dickson <steved@redhat.com>