Try new character detection models [Keras, Tensorflow]

- [ ] Read [this blog](https://nanonets.com/blog/handwritten-character-recognition/) 
- [ ] Try [this other tutorial](https://machinelearningmastery.com/how-to-develop-a-convolutional-neural-network-from-scratch-for-mnist-handwritten-digit-classification/) on our data - compare results. 