TODO

figure out whether an answer is present in a response to a question (should be overridable by each question type if needed) [DONE: 11/05/2014]
port the stats generation from QuizQuestion::Base#stats into the generic answer analyzer
question statistics support:
- Essay [DONE: 29/04/2014]
- Fill in Multiple Blanks
- Fill in The Blank (short_answer)
- Matching
- Multiple Answers
- Multiple Choice
- Multiple Dropdowns
- Numerical
- True/False