Didn't work on OS/X for ruby v.2.4.1 had to link puma and re-install jekyll
gem install puma -v '3.4.0' -- --with-opt-dir=/usr/local/opt/openssl
Then.. Rake couldn't build default task - update the Rakefile
https://jekyllrb.com/docs/installation/#macOS
https://github.com/npiper/neilpiper.blog
Upgrade MacOS Ruby http://codingpad.maryspad.com/2017/04/29/update-mac-os-x-to-the-current-version-of-ruby/
Jekyll https://jekyllrb.com/docs/installation/
Travis-CI Heroku https://docs.travis-ci.com/user/deployment/heroku/#Running-Commands
Heroku CLI: https://devcenter.heroku.com/articles/heroku-cli
Travis-CI Command line https://github.com/travis-ci/travis.rb#general-api-commands
ruby v2.4.1 puma issues puma/puma#783
https://coderwall.com/p/sdxxaa/travis-ci-don-t-know-how-to-build-task-default