Implement 'leaveChat'
Implement 'leaveChat'

Notes:

  Merge branch 'feature/leaveChat' of
  https://github.com/GochoMugo/node-telegram-bot-api into pr/186

References:

  * PR #186: https://github.com/yagop/node-telegram-bot-api/pull/186

yagop/node-telegram-bot-api