Only log errors in exceptions on demand
Only log errors in exceptions on demand

Rather than error logging all of them, allow the user a mechanism
to error log the ones they care about. Also make inner_exception
public so that people can make their own choices.

Change-Id: I15973f52d3d68c24ac8ef7643a53ff0118e892cf

openstack/python-openstacksdk,openstack-infra/shade,openstack-infra/shade,stackforge/python-openstacksdk,openstack/python-openstacksdk,stackforge/python-openstacksdk,dtroyer/python-openstacksdk,dtroyer/python-openstacksdk