Set html language code based on current session

Ghost Userrequested to merge
fix/languagecode-html into master

Closes #835 (closed)

Previous behaviour

Steps to reproduce:

  1. Check the HTML attribute on production when the language is Dutch
  2. It's set to en

New behaviour

Steps to validate that it works:

  1. Check the HTML attribute on production when the language is Dutch
  2. It's set to nl

Merge request reports