sudo: false
language: ruby
rvm:
  - 2.1
  - 2.2
  - 2.3.3
  - 2.4.0
before_install: gem install bundler -v 1.13.6

sudo: false
language: ruby
rvm:
  - 2.1
  - 2.2
  - 2.3.3
  - 2.4.0
before_install: gem install bundler

Install latest version of bundler
Install latest version of bundler
