#1285 timeline upgrade

Timeline feature has been upgraded in this pull request. It now has option to choose between bar or line. And manual interval, if auto (by default) it will use ushahidi interval setting and user can change it to see timeline in appropriate interval.
It also has point value and circle feature to know the actual time where incident happened. It was difficult to know the time of incident as it sometime give straight line when same no of incident happen at multiple time point.
Another improvement is when incident happen at only one time point, it used to not generate line graph so made it to have 0 at start and end for such case similar to the improvement from ushahidi when zero incident.