curds: Rename on-add notification to add-track

This matches the rest of my notification naming style

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

curds/playlist/playlist.py

@@ -12,7 +12,7 @@ class Playlist(list):
     def add(self, track):
         if track is not None and track not in self:
             self.append(track)
-            notify.Notify.notify("on-add", self, track)
+            notify.Notify.notify("add-track", self, track)
 
     def next(self):
         max = len(self) - 1

curds/playlist/test_playlist.py

@@ -77,7 +77,7 @@ class TestPlaylist(unittest.TestCase):
         track = tags.Track.lookup(os.path.join(path, "01 - Test Track 01.ogg"))
         plist = playlist.Playlist("Test Playlist")
 
-        notify.Notify.notify_me("on-add", self.on_add)
+        notify.Notify.notify_me("add-track", self.on_add)
 
         plist.add(track)
         self.assertEqual(self.cb_plist, plist)