lambda2 is missing in gradient of censored_regression2

[Yusuke Nishioka]

https://github.com/wush978/KDD2015wpp/blob/master/WinningPrice.R#L77

It seems lambda2 is missing on regularization term
in gradient calculation of censored_regression2 function.

May I send a PR for this?
If the objective of this repository is the reproduction of the experiment on the paper
and the implementation correctness doesn't matter, I will not.

[Wush Wu]

Thanks for your reply.
I prefer directly fix it and cite this issue.