Add paper references and update challenge.
Add paper references and update challenge.

TUDelft-IN4303-2016/TUDelft-IN4303-2016.github.io,TUDelft-IN4303-2016/TUDelft-IN4303-2016.github.io,TUDelft-IN4303-2016/TUDelft-IN4303-2016.github.io