Add answer and autogradable properties
Add answer to boy_or_girl quetsion
Only one submission per interview question. Fix #1173
Get rid of auto advancing, show correct/incorrect
Add interview question submission answers to user model
If a user has answered the question, show the answer
Show link to next question after answering
Merge pull request #1174 from teamleada/mark-gradable-questions

Autograding questions