Broken links in README

[SuperKogito]

The following links in the README are broken:

• http://www.yelp.com/academic_dataset
• http://www.yelp.com/dataset_challenge

[Sawau]

Hi, I am also facing with this problem.
Did you successfully get the yelp_challenge_dataset now?

[Querela]

Dataset can be found at: https://www.yelp.com/dataset
yelp_challenge_dataset maybe with archive.org?