regress:emulate: add log management support

1) Add log management to support storing logs to files.
2) Add show run statistics at end of emulation.

Signed-off-by: Zhengwang Ruan <ruan.zhengwang@gmail.com>
strategy: add support to store logs to files

Signed-off-by: Zhengwang Ruan <ruan.zhengwang@gmail.com>