Gender doesn't seems optional in db.match_voice()

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What steps will reproduce the problem?
1.Use db.match_voice() without gender argument

What is the expected output? What do you see instead?
It should give the output, instead raise error that 4 arguments required. Even 
with the use of gender it gives error

  File "/usr/local/lib/python2.7/dist-packages/voiceid/db.py", line 370, in match_voice
    gender, self.get_path())
  File "/usr/local/lib/python2.7/dist-packages/voiceid/fm.py", line 741, in wav_vs_gmm
    + gender + '.' + gmm_name + '.seg')
  File "/usr/local/lib/python2.7/dist-packages/voiceid/utils.py", line 102, in ensure_file_exists
    % filename)
IOError: File ash_.ident.M.ashu.gmm.seg doesn't exist or not correctly created

Original issue reported on code.google.com by asharma0...@gmail.com on 7 Jul 2014 at 10:49