Enhance current CityU's Moodle platform so that it allows students to participate in realtime learning activities

1. Livepoll (mod/livepoll)
2. ActiveQuiz (mod/activequiz)

Livepoll

• Add "Show Polling Result" option to allow teachers controlling the appearance of polling result

• Add "Countdown Timer" to the polling acticities. When Time is Up, the polling activities will be closed automatically

ActiveQuiz

• Code refactoring and layout enhancements
• Add "Edit" button to allow teachers editing the question in the quiz page