Added taking quizzes.

I added to functions to quizzes "question" and "answer". Question
displays the question. Answer creates a UserQuestion and UserAnswer
object based on the answer selected by the user. Currently there is
no checking if the session is active or if any of the ids are valid.
I roughly tested it tonight but it was difficult since the results
screen didn't appear to function properly so there may be bugs.
There is also an issue where you can get stuck if a question has
only " " or "" for answers. This shouldn't ever occur as the save
function should delete these questions but currently no deleting
works due to foreign key constraints.