Nr task timer

- After the task is tarted the timer shows up on the event.
- If the task is delayed, the task color changes to red and the timer shows a negative time ( - 1:00).
- Added timer to the event JSON to show the remaining time on the task after it is started.
- Added task_startBtn_time and task_endBtn_time to the event JSON to save start/end time of each task.

Note 1:  Right now the timer shows up right on top of the role circles. This is temporary and we will talk about the best location for the timer in our upcoming meeting. 
Note 2:  "var task_timer_interval" in awareness.js controls the speed of the timer. For now it is fast forwarded ( each second is 1 minute on the timeline). The poll function is being called every few seconds. I decided not to call it every second. As a result, after starting the task, the timer is updated every few seconds.

You need to check if tasks change color after the tasks are delayed and completed. The timer should show the correct remaining time. If the task is delayed the timer should show a negative time. This needs to be tested both in author view and user view.