QAQ gun hui qu
Roll back to single assigner and single assignee. =w=
Add server communication api using AWS SQS service.
Make connection class more general. Finish the setup connection part.
Change the way of verifying initial connection. Use message id as identifier.
Design the register connection pattern.
Merge branch 'master' into 1-2

Since the master branch used NSArray to store user info and doesn't work at all. As we add a server to take care of client request, we do not need the NSArray any more.