Upgrade oslo.vmware>=0.8.0

This release includes several bug fixes (https://launchpad.net/oslo.vmware/+milestone/0.8.0)
as well as many other changes:

969bfba Switch to use requests/urllib3 and enable cacert validation
5b9408f Updated from global requirements
9d9bf2f Updated from global requirements
1ebbc4d Enable support for python 3.x
4dc0ded Updated from global requirements
589ba43 Activate pep8 check that _ is imported

Change-Id: I3912eb965359f1aa29b9313218924ceabd5d839e
Merge "Upgrade oslo.vmware>=0.8.0"