improvements to cross_validation module
improvements to cross_validation module

claesenm/optunity,chrinide/optunity,chrinide/optunity,MarkAWard/optunity,MarkAWard/optunity,MarkAWard/optunity,claesenm/optunity,claesenm/optunity,claesenm/optunity,chrinide/optunity,chrinide/optunity,MarkAWard/optunity