dotfiles should be ignored by dir backend

Was trying to figure out the following

Scanning for music in '/home/public/Music/Chameleon Circuit - Still Got Legs'...
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
TagLib: FLAC::File::scan() -- FLAC stream not found
Traceback (most recent call last):
  File "./zeya.py", line 398, in <module>
    backend = get_backend(backend_type)
  File "./zeya.py", line 314, in get_backend
    return DirectoryBackend(path)
  File "/home/anthony/zeya/directory.py", line 65, in __init__
    self.setup_db()
  File "/home/anthony/zeya/directory.py", line 75, in setup_db
    self.fill_db(previous_db)
  File "/home/anthony/zeya/directory.py", line 205, in fill_db
    song_filename, previous_db)
  File "/home/anthony/zeya/directory.py", line 137, in write_metadata
    file_mtime = os.stat(filename).st_mtime
TypeError: must be encoded string without NULL bytes, not str

It ended up being a stray .AppleDouble folder.

When parsing folders recursively dotfiles and folders should be ignored by default.