message: Replace fit_generator by fit
  Function fit_generator is deprecated, but is still used as an example of
  how to use ImageDataGenerator. This patch fixes the two examples where
  fit_generator is used.
diff: @@ -452,7 +452,7 @@ class ImageDataGenerator(image.ImageDataGenerator):
  # (std, mean, and principal components if ZCA whitening is applied)
  datagen.fit(x_train)
  # fits the model on batches with real-time data augmentation:
  - model.fit_generator(datagen.flow(x_train, y_train, batch_size=32),
  + model.fit(datagen.flow(x_train, y_train, batch_size=32),
  steps_per_epoch=len(x_train) / 32, epochs=epochs)
  # here's a more "manual" example
  for e in range(epochs):
  @@ -486,7 +486,7 @@ class ImageDataGenerator(image.ImageDataGenerator):
  target_size=(150, 150),
  batch_size=32,
  class_mode='binary')
  - model.fit_generator(
  + model.fit(
  train_generator,
  steps_per_epoch=2000,
  epochs=50,
  