language: ruby
rvm:
  - 1.9.3
  - 2.1.0
  - 2.1.1
before_install:
  - gem update bundler

language: ruby
rvm:
  - 2.1.10
  - 2.2.5
  - 2.3.1
before_install:
  - gem update bundler

Build on supported ruby versions only
Build on supported ruby versions only

Prefer minor versions already installed by travis
