language: ruby
rvm:
  - 2.4.0
before_install: gem install bundler -v 1.11.2

language: ruby
rvm:
  - 2.2.4
  - 2.3.0
  - ruby-head
before_install: gem install bundler -v 1.11.2
matrix:
  allow_failures:
    - rvm: ruby-head

Fix test target ruby versions
Fix test target ruby versions

* Change 2.4.0 -> ruby-head (allow_failures)
* Add 2.3.0
* Add 2.2.4
