Made the revision history class deal with empty logs
Made the revision history class deal with empty logs

SoftwareEngineeringToolDemos/FSE-2011-Crystal,KaranDagar/crystalvc,brunyuriy/crystalvc,KaranDagar/FSE-2011-Crystal---old,SoftwareEngineeringToolDemos/FSE-2011-Crystal,KaranDagar/FSE-2011-Crystal---old,SoftwareEngineeringToolDemos/FSE-2011-Crystal,brunyuriy/crystalvc,KaranDagar/crystalvc