title: keras: how to save the training history attribute of the history object
body: <p>In Keras, we can return the output of <code>model.fit</code> to a history as follows:</p>
  
  <pre><code> history = model.fit(X_train, y_train, 
                       batch_size=batch_size, 
                       nb_epoch=nb_epoch,
                       validation_data=(X_test, y_test))
  </code></pre>
  
  <p>Now, how to save the history attribute of the history object to a file for further uses (e.g. draw plots of acc or loss against epochs)?</p>