#90 Added NominalCorrelator
#90 renamed AttributeCorrelator to NumericCorrelator
Merge branch 'master' of https://github.com/prmr/Creco.git into Issue90_NominalCorrelation
#90 Integrated string ranking in the product ranker
#90 Integrated boolean ranking in the product ranker
#90 Added javadoc comments
Merge branch 'master' of https://github.com/prmr/Creco.git into Issue90_NominalCorrelation
Removed test used to debug NominalCorrelator