Upgrading 'stevedore' module for bug 1169730

https://bugs.launchpad.net/ubuntu/+source/cinder/+bug/1169730
Running into this on Ubuntu 12.04

Simply upgrading to a newer 'stevedore' resolved the issues with
the cinder scheduler.

Change-Id: I162c6714d56650fb891ec772bf71126856c82d8c