Rename get_or_add_user_role

get_or_add_user_role is specific to adding a role on a project.
Rename it to get_or_add_user_project_role to allow room for adding a
domain specific role function.

Change-Id: I999308098d22be9800578ae67144a3b687fbc3be
diff --git a/lib/nova b/lib/nova
index c760066..801378d 100644
--- a/lib/nova
+++ b/lib/nova
@@ -383,7 +383,7 @@
         if is_service_enabled swift; then
             # Nova needs ResellerAdmin role to download images when accessing
             # swift through the s3 api.
-            get_or_add_user_role ResellerAdmin nova $SERVICE_TENANT_NAME
+            get_or_add_user_project_role ResellerAdmin nova $SERVICE_TENANT_NAME
         fi
 
         # EC2