mpdsync.py: Remove "file: " prefix from song string in full_sync().

[alphapapa]

Before this change, I was getting this traceback:

Traceback (most recent call last):
  File "mpdsync.py", line 208, in <module>
    main()
  File "mpdsync.py", line 80, in main
    full_sync(master, slaves)
  File "mpdsync.py", line 176, in full_sync
    slave.client.add(song)
  File "/usr/lib/python2.7/dist-packages/mpd.py", line 167, in <lambda>
    return lambda *args: wrapper(command, args)
  File "/usr/lib/python2.7/dist-packages/mpd.py", line 213, in _execute
    return retval()
  File "/usr/lib/python2.7/dist-packages/mpd.py", line 312, in _fetch_nothing
    line = self._read_line()
  File "/usr/lib/python2.7/dist-packages/mpd.py", line 233, in _read_line
    raise CommandError(error)
mpd.CommandError: [50@0] {add} Not found

Now it works with mpd 0.18.7 and 0.19.1 on Ubuntu 14.04 and Debian Jessie.

[alphapapa]

Also moved config file to ~/.config/mpdsync.json and used XDG module to find $XDG_CONFIG_HOME.

[alphapapa]

Also changed shebang to use /usr/bin/env so the script can be executed properly.

[nickpegg]

Since I prefer to use stdlib as much as possible, could you use os.path.expanduser() here instead?

Something like this:

def get_settings(settings_file=os.path.expanduser('~/.config/mpdsync.json')):

[alphapapa]

Yeah, I wondered if it was a good idea to depend on python-xdg, and if it was really necessary. I doubt that many people actually change $XDG_CONFIG_HOME to something other than ~/.config. On the other hand, python-xdg looks to be a fairly standard package (especially on Ubuntu, where software-center depends on it, so it should be installed by default). And it seems like the more "correct" way to do it, rather than hard-coding paths.

But I don't really care very much; I use ~/.config anyway. I suppose the best reason might be to make it easier for potential Windows users, but I don't care much about supporting Windows either, haha!

So, yeah, if you prefer doing it that way, that's fine with me. Thanks.

[nickpegg]

Thanks for the /usr/bin/env thing and cleaning up my whitespace! Pretty sure /usr/bin/which didn't work and was a brainfart on my part when I wrote this script long ago.

[alphapapa]

The whitespace fix there was either an accident or a result of using Emacs, but I'm glad it helped. =)