add python xor example
add python xor example

MiniLight/DeepCL,hughperkins/DeepCL,MiniLight/DeepCL,MiniLight/DeepCL,hughperkins/DeepCL,hughperkins/DeepCL,MiniLight/DeepCL,hughperkins/DeepCL,MiniLight/DeepCL,hughperkins/DeepCL