language: ruby
sudo: false
rvm:
 - 2.4.5
 - 2.5.3

language: ruby
cache: bundler
dist: xenial

branches:
  only:
  - master

matrix:
  include:
    - rvm: 2.4.5
    - rvm: 2.5.3
    - rvm: 2.6.0
  allow_failures:
  - rvm: ruby-head

Update and expand testing in Travis
Update and expand testing in Travis

Test on ruby head and ruby 2.6. Also cache the world and run on xenial

Signed-off-by: Tim Smith <764ef62106582a09ed09dfa0b6bff7c05fd7d1e4@chef.io>
