Add Sum

[qqj1130247885]

Create A Good Pull Request

下面的文字请保留在PR说明的最后面，并在提完PR后，根据实际情况勾选确认以下情况

Please check the follow step before merging this pull request

• [x] Python code style verification
• [x] Review all the code diff by yourself
• [ ] All models(TensorFLow/Caffe/ONNX/PyTorch) testing passed
• [ ] Details about your pull request, releated issues

If this PR add new model support, please update model_zoo.md and add model to out test model zoos(@wjj19950828)

• [ ] New Model Supported
• [ ] No New Model Supported

主要贡献：

1 增加对version7下的sum的单测程序（不支持broadcast） 2 增加对version8-15下的sum单测程序（支持broadcast）