Create Basic Backend

[PercyJiang]

No PR involved.

Verify the endpoints work

1. POST http://ec2-3-89-202-113.compute-1.amazonaws.com:8080/message-board/post
2. { "source": "reviewer", "content": "hello" }
3. GET http://ec2-3-89-202-113.compute-1.amazonaws.com:8080/message-board/getAll