language: ruby
rvm:
  - 2.0.0-p598
  - 2.1.6
  - 2.2.4
  - 2.3.0
  - ruby-head
matrix:
  allow_failures:
    - rvm: ruby-head

language: ruby
rvm:
  - 2.0.0
  - 2.1.10
  - 2.2.6
  - 2.3.3
  - ruby-head
matrix:
  allow_failures:
    - rvm: ruby-head

Update TravisCI ruby versions tested against.
Update TravisCI ruby versions tested against.

Note: Ruby 2.4 not yet added to this list, since rvm has not released a
version supporting this yet. (It is only on the unreleased master
branch, so I have currently just installed+tested it locally.)
