Upgrading to slack-ruby-bot 0.3.1 breaks logging

[dblock]

Logging by default now silences both slack-ruby-client logger and slack-ruby-bot logger. Before logger.info in a service was giving output like

19:13:03 web.1  | I, [2016-07-10T19:13:03.600479 #29229]  INFO -- : Starting team game=pong, name=dblock, domain=dblockdotorg, id=T04KB5WQH.
19:13:08 web.1  | I, [2016-07-10T19:13:08.363012 #29229]  INFO -- : Successfully connected to https://dblockdotorg.slack.com.

This is because of Loggable singleton implementation introduced in #84.

  module LoggingMethods
    def logger
      Loggable.logger
    end
  end