Introduce feature tests for recent PHP versions in language core update #148

Feature Request

• Yes, I reviewed the contribution guidelines.

Describe your use case and the problem you are facing

Current test scenario is pretty restricted:

@require-php-5.6 @less-than-php-7.0
  Scenario Outline: Core translation update

It would be good to expand test for more and WP/PHP combinations.

Describe the solution you'd like

Expanded tests.