Converting single choice questions with pictures to coursera docx

Created by: AnneliKlamas

• creating coursera docx
• create endpoint for downloading coursera docx
• add single choice questions to coursera docx
• add pictures to coursera docx
• add feedback to coursera docx answers
• add answers to coursera docx questions

added backend label

assigned to @klamas

added in code review label

mentioned in issue #23 (closed)

closed