MDL-10109 New category gets created without problem, and the outcomes are created...

MDL-10109 New category gets created without problem, and the outcomes are created and added as children of that category. The normal grade_item, if present, is also added before the outcomes.

There is only one issue which is probably not directly related to this issue: When these new objects are created, the changes take a few page loads to appear correctly in the grader report. Sometimes I even had to open the Category and item edit page and then the grader report again before the correct changes would appear and remain that way afterwards