Additional EDA plots

[mwinton]

1. Apply the resampling logic from our code to see what the audio waveforms look like after resampling. (The current value of the SAMPLE_RATE constant in mel_params.py is 16000.)

2. Generate a mel spectrogram of the resampled audio and plot that. That way we will be able to visualize the image in the same format that the model will train on. I think that will help us pick some species to classify which show some visual distinction.