Clear paper by De Groeff et al in CCS '12
Cleared paper by Chugh et al. in OOPSLA '12
Problem with Jin et al., PLDI '12: Dead URL

The URL mentioned in the paper and used by Collberg et al. is now dead;
I plan to follow up with the papers' authors.
Merge pull request #43 from ricci/master

Clear two disputed papers, and found a problem (dead link) with a third