**Description**
Use config `log_raw_data` to control whether log the raw data into file or not. The default value is `no`. We can set it as `yes` for some particular benchmarks to save the raw data into file, such as NCCL/RCCL test.
**Description**
Revise the DockerBenchmark base to support image pull, image rm etc.
**Major Revision**
- image pull in _preprocess()
- image clean in _postprocess()
- execute customized commands in _benchmark()
- add unit tests