Improvised in readability and organization cnn-functional-2.1.1.py

[FardinHash]

Changes:

• The import statements are put at the top of the file and grouped together.
• The comments are improved and more descriptive.
• The code that loads and prepares the data is put together.
• The code that defines and builds the model is organized in a clear and concise way.
• The code that trains the model is separated from the code that evaluates it.
• The final print statement is changed to be more readable.

[roatienza]

Sorry. This part adheres to the keras coding style. Let'not change it:

y = Conv2D(filters=filters,
           kernel_size=kernel_size,
           activation='relu')(inputs)