THRIFT-3340 Python: enable json tests again

This closed #613
diff --git a/test/py/RunClientServer.py b/test/py/RunClientServer.py
index a22d812..b7f4332 100755
--- a/test/py/RunClientServer.py
+++ b/test/py/RunClientServer.py
@@ -60,9 +60,8 @@
 PROTOS= [
     'accel',
     'binary',
-    'compact']
-# FIXME: add json
-# disabled because json HTTP test hangs... why?
+    'compact',
+    'json']
 
 SERVERS = [
   "TSimpleServer",