Framework: DataRequest implementation

More to add before merging:
- [x] Http handlers
- [x] TestFrameworkDataRequest
  - [x] reached ServeAsX
  - [x] id, req, data is correct
- [x] Close go routines at the end of lifecycle (Note: http server isn't closed. We need graceful shutdown solution.)
  - [x] close go routine
@xiang90 
Any idea on this? I think it's correct to create a new handler.