sudo: false
language: ruby
rvm:
  - 2.3.1
before_install: gem install bundler -v 1.13.2
script: rake spec

sudo: false
language: ruby
rvm:
  - 2.4.0
  - 2.3.3
  - 2.2.6
  - 2.1.10
  - 2.0.0
before_install: gem update bundler --no-document
script: rake spec

Add CI target rvm version from 2.0 to 2.4
Add CI target rvm version from 2.0 to 2.4
