Add oslo.log

Install the oslo.log library from source so the gate tests
are run against master.

Change-Id: Id2925ce733773d8189ecc0d24b0384c44fad7b72
diff --git a/stackrc b/stackrc
index d58c279..5ea9705 100644
--- a/stackrc
+++ b/stackrc
@@ -236,6 +236,10 @@
 OSLOI18N_REPO=${OSLOI18N_REPO:-${GIT_BASE}/openstack/oslo.i18n.git}
 OSLOI18N_BRANCH=${OSLOI18N_BRANCH:-master}
 
+# oslo.log
+OSLOLOG_REPO=${OSLOLOG_REPO:-${GIT_BASE}/openstack/oslo.log.git}
+OSLOLOG_BRANCH=${OSLOLOG_BRANCH:-master}
+
 # oslo.messaging
 OSLOMSG_REPO=${OSLOMSG_REPO:-${GIT_BASE}/openstack/oslo.messaging.git}
 OSLOMSG_BRANCH=${OSLOMSG_BRANCH:-master}