Have a way to disable Glance v1 in devstack

As part of the process of deprecating Glance's V1, the glance team would
like to start testing V2-only environments. Therefore, this change
provides a way to force other services to use V2.

Change-Id: I87e77d07964eac01e9a796817cbc88bd6e59c721
diff --git a/lib/cinder b/lib/cinder
index 1786232..7763599 100644
--- a/lib/cinder
+++ b/lib/cinder
@@ -342,6 +342,10 @@
         iniset $CINDER_CONF DEFAULT glance_ca_certificates_file $SSL_BUNDLE_FILE
     fi
 
+    if [ "$GLANCE_V1_ENABLED" != "True" ]; then
+        iniset $CINDER_CONF DEFAULT glance_api_version 2
+    fi
+
     # Register SSL certificates if provided
     if is_ssl_enabled_service cinder; then
         ensure_certificates CINDER