WIP: First pass at creating BDD tests for the Problem Creation stories

These tests are a first attempt at defining the story. The underlying methods are all empty, and will be filled out with the implementation.  I believe some steps may overlap and need to be refactored, and perhaps some of the stories belong in common_grading instead of peer_grading. I want @wedaly  to review this and see if I'm going down the correct path before I fill out any more of these for the first sprint.