yahoocsvfeed: set ticker from file name

src/nailab/data/yahoocsvfolderdatasource.py

@@ -34,7 +34,9 @@ class YahooCsvFolderDataSource(DataSource):
         for path, f_id in self.feeds:
             if f_id == feed_id:
                 with open(path, 'r') as f:
-                    return YahooCSVFeed(f)
+                    feed = YahooCSVFeed(f)
+                    feed.set_ticker(feed_id)
+                    return feed
         raise NailabError('Unable to obtain feed: {}'.format(feed_id))