handler.py: Add quiet mode
handler.py: Add quiet mode

Create a quiet configuration option to disable the logger from
setting up the StreamHandler to output to stdout.

Normal logging to a log_file is unaffected.

Signed-off-by: Rob Woolley <a7d8b90bbdfdfa8ce7f587158d7158129e0bbc0e@windriver.com>

rcwoolley/device-cloud-python,rcwoolley/device-cloud-python