Visualization clarification

[zakv]

Fixes #85.

Changes proposed in this pull request:

• Rename the GaussianProcessVisualizer methods plot_hyperparameters_vs_run and plot_noise_level_vs_run to end in vs_fit().
  • Update the x-axis labels and docstrings to say fit number.
  • Mention that there is one fit per generation in the docstring.
  • Keep the methods with the old "vs_run" names for now. Make them issue a deprecation warning then call the methods with the new names.
• Update the argument names in GaussianProcessLearner.create_visualizations() to reflect the new method names.
  • Add **kwargs and check for old variable names for backwards compatibility. Issue a deprecation warning if they are used.
  • Update docstring.
• Change the docstring, x-axis label, and title in NeuralNetVisualizer.plot_losses() to say epochs instead of training run.
  • Change the indices on the x-axis to be 0, 10, 20... instead of 0,1, 2... since those are the number of epochs.
  • Mention in the docstring that the loss is recorded every 10 epochs.
• Update visualizations.rst to reflect the changes.