rebaseline_server JSON: pass category values as values, not keys

gm/rebaseline_server/imagepairset_test.py

Index: gm/rebaseline_server/imagepairset_test.py
diff --git a/gm/rebaseline_server/imagepairset_test.py b/gm/rebaseline_server/imagepairset_test.py
index c046ec7c7cf6e5e24587439ada4d0c7599fb7912..37be0fe63719a60e2139fce457fd3acea07e5119 100755
--- a/gm/rebaseline_server/imagepairset_test.py
+++ b/gm/rebaseline_server/imagepairset_test.py
@@ -88,12 +88,11 @@ class ImagePairSetTest(unittest.TestCase):
     expected_imageset_dict = {
         'extraColumnHeaders': {
             'builder': {
+                'counts': [3],
                 'headerText': 'builder',
                 'isFilterable': True,
                 'isSortable': True,
-                'valuesAndCounts': {
-                    'MyBuilder': 3
-                },
+                'values': ['MyBuilder'],

[borenet, 2014/05/08 12:40:18]

My concern with this format is that it's possible for the two lists to be out of
sync.  What if we used tuples or lists to create pairs:

'valuesAndCounts': [
  ('MyBuilder', 3),
]

[epoger, 2014/05/08 15:04:35]

JSON doesn't have a concept of tuples, but I could use a list of 2-item lists. 
I'll try that and see how it goes.  As you note, that will inherently guard
against out-of-sync lists.

Thanks for the suggestion.  It could make things a bit more complicated on the
client side, but we'll see.

             },
             'test': {
                 'headerText': 'which GM test',