Merge pull request #3 from nwpan/master

updating sync_with_neighbour_queue
final_rating_result() now returns list for choices and clock instead of a json string. merge_db function now inserts the result in the digest_list
Merge branch 'master' of https://github.com/kkc47/Distributed-System--Rating-System
added comment on example params for merge_clock
changing usage