update publish date on launch for new articles, and initial work to add unit tests including refactoring
add unit test for publication date update code
add another test for the discard function
more factoring out and use the FreeSpec to put multiple tests in one method
move the pure stuff to another class to make the separation clearer
Merge pull request #6777 from guardian/update-pubdate-on-merge

update the published date when you move something from draft to live on the fronts editor tool