This really should be covered by a test, sorry I don't have time to do that myself.
Without this, any request causes
2017-01-23T19:00:28.900703+00:00 app[web.1]: INFO /app/lib/pagerbot/slack_adapter.rb:55:in `block in <class:SlackAdapter>': {:token=>"REDACTED", :nick=>"xavier", :channel_name=>"testing", :text=>"pagerbot help", :user_id=>"REDACTED", :adapter=>:slack}
2017-01-23T19:00:28.900965+00:00 app[web.1]: 2017-01-23 19:00:28 - NameError - uninitialized constant Pagerbot::Parsing:
2017-01-23T19:00:28.900966+00:00 app[web.1]: /app/lib/pagerbot/slack_adapter.rb:63:in `block in <class:SlackAdapter>'
2017-01-23T19:00:28.900968+00:00 app[web.1]: /app/vendor/bundle/ruby/2.2.0/gems/sinatra-1.4.7/lib/sinatra/base.rb:1611:in `call'