Fixed some bugs in Category and Path based recommenders
Included recency and popularity information into the CategoryBasedRecommender
Fixed NullPointerException when a new domain is asked to be recommended
Update forbidden items when an update is received from impressions
Package refactoring: net.recommenders.plistacontest.recommender --> net.recommenders.plista.rec
Package refactoring: net.recommenders.plistacontest.utils --> net.recommenders.plista.utils
Merge pull request #2 from abellogin/master

Fixed bugs in contest recommenders and package refactoring