Fix os_glance role functional testing

Without this change the role is failing functional tests with an
"ImportError: No module named yaml" which leads to a Broken Pipe
error as seen in change-set 1.

Change-Id: I359556db6fa3e9f75dae609966efe59f4794379a

run_tests.sh

@@ -53,3 +53,4 @@ for tox_env in $(awk -F= '/envlist/ {print $2}' tox.ini | sed 's/,/ /g'); do
     fi
   fi
 done
+

tests/test-glance-functional.yml

@@ -22,6 +22,7 @@
     - python-glanceclient
     - python-keystoneclient
     - httplib2
+    - pyyaml
 
 - name: Check the glance-api
   uri: