hangman: bug fix
hangman: bug fix

- add judge clue for perfect-solve
- fix invalid syntax
  - in prev impl, `!word` statement makes `slackid` of the playing user `undefined`.

tsg-ut/slackbot,tsg-ut/slackbot,tsg-ut/slackbot,tsg-ut/slackbot,tsg-ut/slackbot,tsg-ut/slackbot