Users can see multi-choice responses

Trello Card: https://trello.com/c/5D4WsPuo/22-users-can-respond-to-multi-choice-questions

NOTE: From the survey show page, click on "Survey responses" to view responses.

NOTE: Currently, users need to submit individual answers to individual questions. When refactoring, we plan to only require users to submit the survey once and capture all answers.
Don't abbreviate: `response`, not `r`