HW1-1C.2 - intermediate commit

* Added support in content controller and spec to call merge.
* Stubbed the functionality in the model to actually do the merge.
* Have not yet implemented the functionality in the model to do the merge.
HW1-1C - Finished implementation of merge functionality in controller and model.

* Cleaned up specs in content_controller to test for calling merge_articles,
  * destroying the orignal articles, and redirecting as expected.
* Added specs in article_spec to test merging of articles, happy and sad paths
* Implemented Article.merge_articles in article.rb

Still need to finish getting the remaining cucumber scenarios to all pass.
HW1-1C - completed implementation and tests

* Rest of cucumber test now passing (scenarios 3-5)
  * Added xpath matching for author and title in articles index list
  * Added comments to each article, and check for merged comments
  * Added other necessary step definitions
* I believe all the functionality and testing is now complete for HW1-1