Follow up for https://review.openstack.org/#/c/236007
This fixes following minor items:
- Fix a 'raise Exception class' syntax to 'raise Exception instance'
- Use original eventlet.Timeout instead of swift.exceptions.Timeout
imported from eventlet.Timeout
- Change Timeout to initiate w/o args (1st arguments should be timeout
second and we don't have to set None if we don't want to set the sec)
- Add a message argument to some Exception instances
Change-Id: Iab608cd8a1f4d3f5b4963c26b94ab0501837ffe1
fd30df6e65