[tmux] Added music symbol, updated interval

+ added music symbold to spotify/itunes scripts
+ changed refresh interval from 5 seconds to 20 seconds

bin/itunes.applescript

@@ -4,7 +4,7 @@ if application "iTunes" is running then
       set theName to the name of the current track
       set theArtist to the artist of the current track
       try
-        return theName & " - " & theArtist
+        return "♫ " & theName & " - " & theArtist
       on error err
       end try
     end if