git-svn: bail out on incorrect command-line options

git-svn: bail out on incorrect command-line options

"git svn log" is the only command that needs the pass-through
option in Getopt::Long; otherwise we will bail out and let the
user know something is wrong.

Also, avoid printing out unaccepted mixed-case options (that
are reserved for the command-line) such as --useSvmProps
in the usage() function.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>