Sylvia/docs/doc 759

@jmclaus Hey Jean-Michel - I can't get this to work. When I create the component in my toy course, there's just a big blank box where the molecule should be. Can you look through this and let me know if some of the instructions are wrong? Thanks!
This is in the **8. Creating Exercises and Tools** (http://edx.readthedocs.org/projects/edx-partner-course-staff/en/latest/exercises_tools/index.html) section of the course authors guide, so the user will already be in the unit where he wants to create a particular problem or tool.