add missing game_mode const values

Added other game mode values (consts and docstrings) and changed "all-pick" to "all pick".

Sources:
http://wiki.teamfortress.com/wiki/WebAPI/GetMatchDetails
https://bitbucket.org/VoiDeD/steamre/src/0152b728b88103ceb8afdaa8b157927135451d8d/Resources/Protobufs/dota/dota_gcmessages.proto?at=default#cl-246