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
diff --git a/test-requirements.txt b/test-requirements.txt
index 215f28b..13ef291 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -8,3 +8,4 @@
 mock>=1.0
 coverage>=3.6
 oslotest
+stevedore>=0.14