resolve sdkserver restart error and enhance log
resolve sdkserver restart error and enhance log

1. resolve sdkserver restart error: failed to bind port
set option reuseaddr to server socket so that the server can reuse
this addr and port when restart.

2. Enhance sdkserver debug log.
Add more debug info to sdkserver: add client addr and thread name
to each log record.

Change-Id: I58255b161d78021d995b51e9242ce49ddabf856a

mfcloud/python-zvm-sdk,mfcloud/python-zvm-sdk,mfcloud/python-zvm-sdk,mfcloud/python-zvm-sdk