LU-2467 utils: Update wirecheck for new connect flags

LU-2467 utils: Update wirecheck for new connect flags

This patch adds OBD_CONNECT_PINGLESS to wirecheck and updates
wiretests accordingly.  Also, the connect flag readme comment is
updated to include this as a guidance for adding connect flags in the
future.

Signed-off-by: Li Wei <wei.g.li@intel.com>
Change-Id: I131291dd2dcfda07045a09cbfde4833128464966
Reviewed-on: http://review.whamcloud.com/5269
Reviewed-by: Niu Yawei <yawei.niu@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>