language: ruby
rvm:
  - 2.2.2
before_install: gem install bundler -v 1.10.4

language: ruby
rvm:
  - 2.2.4
  - 2.2.3
  - 2.2.2
  - 2.1.8
before_install: gem install bundler -v 1.10.4

Add additional ruby versions to CI matrix
Add additional ruby versions to CI matrix

Support ruby 2.1+
-----------------

Required keyword arguments weren't introduced until ruby-2.1. The
forking_resolution_strategy.rb makes use of required keyword arguments
to ensure that the caller passes a 'promise' for resolution.
