common: add cifs support

Pass -cifs argument from the command line to enable cifs testing
for $TEST_DEV. Also mention CIFS and missed UDF in README.

Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Reviewed-by: Steve French <smfrench@gmail.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

check

@@ -68,6 +68,7 @@ usage()
 
 check options
     -nfs                test NFS
+    -cifs               test CIFS
     -tmpfs              test TMPFS
     -l			line mode diff
     -udiff		show unified diff (default)
@@ -205,6 +206,7 @@ while [ $# -gt 0 ]; do
 	-\? | -h | --help) usage ;;
 
 	-nfs)	FSTYP=nfs ;;
+	-cifs)	FSTYP=cifs ;;
 	-tmpfs)	FSTYP=tmpfs ;;
 
 	-g)	group=$2 ; shift ;