v2.0-RC.1
- remove all cgo dependences, now the OJ & prepare are pure go implementation
- fix the timeout of website
- delete useless 'mark'
- better prepare.go script with download progress
- rewrite replica enable/disable logic to 4 statuses, this logic add a channel to implement async callback
- allow player to open the challenge after submitting flag
- allow player to startup the challenge environment after submitting flag