language: ruby
rvm:
  - 2.1
  - 2.2
  - 2.3.0
  - 2.4.0
before_install: gem install bundler -v 1.13.7

sudo: false
language: ruby
cache: bundler
rvm:
  - 2.1.10
  - 2.2.9
  - 2.3.6
  - 2.4.3
  - 2.5.0
  - ruby-head
before_install:
  - gem update --system
  - gem install bundler --no-document

Update Travis config: cache bundler, new rubies
Update Travis config: cache bundler, new rubies
