实现P2P指定文件夹下的动态同步功能，支持新加入文件同步，不支持删除文件同步-when a peer establish a TCP connection with another peer, both of them will compare the lists of files they possess(assume that these shared files are stored in a designated folder in each peer), and proceed to exchange files so that they both have exactly the same files. A TCP connection must remain open until a user manually terminates the peer process at either end of hte connection. During the time when the connection remains open, any new file addition to the designated folder of any peer must be propagated to the other connected peers in the overlay network. remain open until a user manually terminates the peer process at either end of hte connection. During the time when the connection remains open, any new file addition to the designated folder of any peer must be propagated to the other connected peers in the overlay network.