Updated (custom) Candy distribution; fix chatroom

* Fix chatroom to use the calculated course room, rather than the
  testing-only 'dev' room.
* Install new version of candy.min.js compiled with an Aria tag for the
  input box (see also:
  https://github.com/jrbl/candy/tree/input-accessibility-improvement)

Co-authored-by: Giulio Gratta <caeser2164@gmail.com>
Co-authored-by: Nate Hardison <natehardison@gmail.com>