Updated to Ruby 2.4.1.
Updated to Ruby 2.4.1.

- Details:
  - https://www.ruby-lang.org/en/news/2017/03/22/ruby-2-4-1-released
  - https://medium.com/rubyinside/ruby-2-4-1-released-whats-changed-fa83346c93f3

bkuhlmann/resourcer