Made the default parser language configurable

**Feature:** Configurable default parser language
  As a feature writer
  I want to set a default feature file language
  So that I do not have to write # language: xx in every file

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I have some troubles running the unit-test suite, even on a clean checkout of `develop`. See the specific error below.
Also I am unsure how to write an effective unit-test for this simple change. Suggestions are welcome.

This PR is related to <behat pr>