Added editing ability
Fixed token field in MySQL
Added selective question statistics
New service: GetQuestionSVC
Now sending only question id to students
Pre-formatting questions before broadcast
Proper field name in MySQL
Storing basic question stats in MySql
Unregister both teacher's and student's expired tokens
Minor SQL optimizations
Reformatted code
Not storing last_result_uuid anymore
Added TeacherSummarySVC
PHP tests optimizations
Reformatted code
Moved helper functions to separate file
Added question_id in buildQuestions
Teacher is notified about new answers submitted
Added option to send is_correct variable for answers
Better statistics formatting