Static Ranking System

Created Files:
* UpdateLeaderBoard.php: A script which would be scheduled to run every 2 minutes during the contest. It would calculate the Rankings of the current Contest and save it in the 'ranktable' attribute of the 'contest' table in JSON format.

* Leaderboard.php: A Utility class which contains public methods to update the LeaderBoard content and fetch static Rank for a Particular contest Code.

Updated Files:
* components.php: removed the dynamic rank calculation code snippet and placed it in Leaderboard Utility Class.

* rank.php: made slight changes to fetch the static ranking page