`answers-name` not Accounted For

At several points, the `data['submitted_answers']` dict is indexed without using the problem's `answers-name` attribute to get data, eg
```py
data['submitted_answers'][answers_name + 'student-parsons-solution']
```
where `answers_name` is set on the `question.html` file, and will soon be required by the element to process.

PL must have figured a way around this because it's their usual setup.

### Note:
After refactoring the backend, the solution will simply be stored at
```py
data['submitted_answers'][answers_name]
```