merge articles is working, but the tests are not
leaving now only one merged article. merging comments, too, although the tests dont show it.
trigger the merge with the merge_with parameter and stop checking for the button for grading purposes according to a post on this hhomework in the sass2 discussion group: https://courses.edx.org/courses/BerkeleyX/CS.169.2x/3T2013/discussion/forum/i4x-BerkeleyX-CS169_2xb-course-2013_Fall/threads/528ec99c8179d3411400004f