Require stevedore for check_uptodate.sh

The Oslo config generator imports the stevedore.named module but
stevedore isn't listed as a requirement for Tempest, so config
generation can fail with an ImportError.

Closes-Bug: #1333998

Change-Id: I47ecac0f5881aceb279391a981780a2dd72f0d2b
Merge "Require stevedore for check_uptodate.sh"