fixed compatibility issues in util.py
fixed compatibility issues in util.py

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