before_install:
 - gem install bundler
language: ruby
matrix:
    include:
    - rvm: "2.1.4"
    - rvm: "2.2.0"
    - rvm: "2.3.1"

before_install:
 - gem install bundler
language: ruby
matrix:
    include:
    - rvm: "2.1.4"
    - rvm: "2.2.0"
    - rvm: "2.3.1"
    - rvm: "2.4.1"

Add test for Ruby 2.4.1
Add test for Ruby 2.4.1
