Fix: missed a callback.
Fix: missed a callback.

dblock/slack-ruby-bot-server,dblock/slack-ruby-bot-server,dblock/slack-bot-server,dblock/slack-bot-server,dblock/slack-bot-server,dblock/slack-bot-server,slack-ruby/slack-ruby-bot-server,slack-ruby/slack-ruby-bot-server,dblock/slack-ruby-bot-server,slack-ruby/slack-ruby-bot-server