fix travis dependency blocker

.travis.yml

@@ -3,6 +3,7 @@ dist: trusty
 rvm:
 - 2.4.4
 before_script:
+  - bash etc/ci-setup.sh
   - gem install bundler -v 1.16.2
   - bundle exec rake hatchet:setup_travis
 addons:

etc/ci-setup.sh

@@ -0,0 +1,3 @@
+sudo apt-get -qq update
+sudo apt-get install software-properties-common -y
+curl --fail --retry 3 --retry-delay 1 --connect-timeout 3 --max-time 30 https://cli-assets.heroku.com/install-ubuntu.sh | sh