Markhoeber/documentation/stud 1260

See draft documentation at:  http://draft-nested-components.readthedocs.org/en/latest/organizing_course.html#nested-components
do all of the components need to end up in a group? can you leave them in Inactive Groups, or do you have to delete them? Do you have to have one component per group, or could you leave a group without any component? (maybe make reference to the examples of changing from three to two, or from two to four, where in one case you have to deal with an extra component and in the other you'll have to add some...?)