Update to Ruby 2.4.0

[benjaminoakes]

https://www.ruby-lang.org/en/news/2016/12/25/ruby-2-4-0-released/

[mattigilmore]

how am I going to update ruby for you its on your machine.

[benjaminoakes]

https://github.com/techcorridorio/techcorridorio.github.io/blob/master/.ruby-version

Needs to still work with the gems and generate the site correctly.

[mattigilmore]

I'll install the ruby later and see if it works