rebaseline_server: make intermediate JSON specify base urls for diff images

BUG=skia:1919,skia:2230
NOTREECHECKS=True
NOTRY=True
R=rmistry@google.com

Author: epoger@google.com

Review URL: https://codereview.chromium.org/196533021

git-svn-id: http://skia.googlecode.com/svn/trunk@13830 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/rebaseline_server/server.py b/gm/rebaseline_server/server.py
index 19b0035..396f42d 100755
--- a/gm/rebaseline_server/server.py
+++ b/gm/rebaseline_server/server.py
@@ -330,6 +330,8 @@
       now = int(time.time())
       response_dict = {
           results_mod.KEY__HEADER: {
+              results_mod.KEY__HEADER__SCHEMA_VERSION: (
+                  results_mod.REBASELINE_SERVER_SCHEMA_VERSION_NUMBER),
               results_mod.KEY__HEADER__IS_STILL_LOADING: True,
               results_mod.KEY__HEADER__TIME_UPDATED: now,
               results_mod.KEY__HEADER__TIME_NEXT_UPDATE_AVAILABLE: (