v0.3.0

• Adds logging via a LogWriter class (and in contrib, a TensorBoardWriter class)
• Refactors the ModelTuner class
• Renames Classifier.train to Classifier.train_model to avoid overwriting the nn.Module.train function
• Adds support for metrics requiring predicted probabilities (like ROC-AUC)
• Better handling of EndModel construction
• Other fixes and additions focused on EndModel training