test_demo/test_main for dcc project

--usage: ./dcc_main nodeid cfg_str

--example: ./dcc_main 1 '[{"stream_id":1,"node_id":1,"ip":"127.0.0.1","port":1701,"role":"LEADER"}, {"stream_id":1,"node_id":2,"ip":"127.0.0.1","port":1702,"role":"FOLLOWER"},{"stream_id":1,"node_id":3,"ip":"127.0.0.1","port":1703,"role":"FOLLOWER"}]'