Save complete tracks and albums to the db for faster startup

- refactor function locations
- add logger
- check for new tracks instead of re-processing all files

server/app/instances.py

@@ -4,7 +4,7 @@ All the MongoDB instances are created here.
 
 from app.db import artists, albums, trackcolors, tracks, playlists
 
-songs_instance = tracks.AllSongs()
+tracks_instance = tracks.AllSongs()
 artist_instance = artists.Artists()
 track_color_instance = trackcolors.TrackColors()
 album_instance = albums.Albums()