Feature/pbl

Feature Request: PBL System corpus-client-app#179 (closed)

Streak: A streak is started when a user makes a contribution and no existing streak is ongoing. A streak last for 24 hours. When in a streak, the user will earn increasingly more number of points for the next contribution they make. This can be displayed as a streak multiplier (example x25). When the streak ends, the multiplier will reset to x1 and the streak will have to be restarted by making a contribution. This will cause every next contribution to reward much more points and will incentivize users to keep contributing to make the streak higher.