A fairly big batch of changes, blame me to forget committing

Changes in no particular order:
- Replaced all use cases of wavfile/wave and extract_channels with the new decoder.read function
- Added a 'recognize' method to the Dejavu class. This is a shortcut for recognizing songs.
- Renamed 'do_fingerprint' into 'fingerprint_directory'
- Removed parameters not required anymore from fingerprint_directory
- Cleaned up fingerprint.py
- Made fingerprint.generate_hashes a generator
- WaveFileRecognizer is now FileRecognizer and can take any formats supported by pydub
- Fixed MicrophoneRecognizer to actually run, previous version had many small mistakes
- Renamed 'fingerprint_worker' to '_fingerprint_worker' to signify it is not to be used publicly
- Moved 'chunkify' outside the Dejavu class
- Cleaned up pep8 styling mistakes in all edited files.