support input and output with json file

[yangdongsheng]

ubbdadm map --type cache --cache-dev-type file --cache-dev-file-filepath /dev/ram0 --backing-dev-type rbd --backing-dev-rbd-pool rbd --backing-dev-rbd-image yds_testimg --cache-mode writeback --num-queues 32

support input and output with json file