Remove -i alias for -I in hashpipe_dump_databuf

hashpipe_dump_databuf had accepted the -i option as an alias for the -I
option.  The -i option to hashpipe_dump_databuf is no longer supported.
Change hashpipe_check_databuf -i option to -d

The -i/--id option to hashpipe_check_databuf has been changed to
-d/--databuf.  The lowercase -i option was too easily confused with the
uppercase -I option and the --id option was not so descriptive as the
--databuf option.
Add -h/--help option to hashpipe_clean_shmem