Refactor onRequest as Event-driven asynchronous callbacks

Author:    Hoa Hoang <nobi.hoa@gmail.com>
Split to server module

Author:    Hoa Hoang <nobi.hoahm@gmail.com>
Add router module

Author:    Hoa Hoang <nobi.hoa@gmail.com>
Add requestHandlers module

Author:    Hoa Hoang <nobi.hoa@gmail.com>
Not to do: blocking operation

Author:    Hoa Hoang <nobi.hoa@gmail.com>
Fix non-blocking operation

Author:    Hoa Hoang <nobi.hoa@gmail.com>
Handler POST request

Author:    Hoa Hoang <nobi.hoahm@gmail.com>