Append fix

Summary:
Fixes #233 by checking for the existence of new_data that is unnamed, which makes append work for unnamed traces again. It also fixes inserting a new unnamed trace.
Closes #234

Differential Revision: D6638379

Pulled By: JackUrb

fbshipit-source-id: 548e3e6d17d54d21c62193d90c7a48cb9c6f0988

py/server.py

@@ -419,7 +419,7 @@ def update(p, args):
             return UpdateHandler.update_updateTrace(p, args)
         p = update_window(p, args)
         name = args.get('name')
-        if name is None:
+        if name is None and new_data is None:
             return p  # we only updated the opts or layout
         append = args.get('append')