Revert a problematic index change in bluesky#34.

This conflicts with indexing requirements imposed by databroker.v0.
We need old versions of databroker.v0 to work against the same database
as this does.

suitcase/mongo_normalized/__init__.py

@@ -67,7 +67,7 @@ def _create_indexes(self):
 
         If the index already exists, this has no effect.
         """
-        self._resource_collection.create_index('uid', unique=True)
+        self._resource_collection.create_index('uid')
         self._resource_collection.create_index('resource_id')  # legacy
         # TODO: Migrate all Resources to have a RunStart UID, and then make a
         # unique index on: