Custom batch size for InfoGAN

[mridulbirla]

For issue #19 We need to pass batch size also when calling generator to predict an image. Following are the changes:

1. In data_utils, Function get_disc_batch and plot_generated_batch call's predict function on generator model. As per Keras documentation(https://keras.io/models/sequential/) , we need to pass batch_size variable. Previously it didn't gave error because batch_size was 32 and predict function default batch_size is 32.

[tdeboissiere]

Good catch, thanks !