Integrate Ping API and the timer

[pawanrawal]

1. /validate would also return a duration along with the token on successful authentication. This duration should be shown on the instructions screen and the initial time left should be the same as this.
2. /ping needs to be called on every 5 sec in a background function after the quiz starts and until it is finished. It will return the time_left, this has to be synchronized with the total time left for the quiz.
3. There should also be a time taken for each question which can be managed on the client side and should be reset on showing a new question.

[Rahul-Sagore]

This is done, Need to test properly for possible bugs.

[pawanrawal]

The instructions screen doesn't show the time from the /validate API. It still shows 60 mins. Also we can rename Time Taking to Time Taken. Apart from that looks fine. Will test it more thoroughly.