Java Neural Network Library

Hi, I’ve build [my own version](https://github.com/kim-marcel/basic_neural_network) of this neural network library in Java. It has the same functionality as this one but I’ve added some extra features like saving/ reading the neural network to/ from JSON-file and support for multiple hidden layers. The library can be downloaded as a jar and used in Java or Processing projects.

These are two examples that use my library:
- [Solving XOR with nn in Java](https://github.com/kim-marcel/xor_with_nn)
- [Doodle classification in Processing](https://github.com/kim-marcel/doodle_classifier)

Besides me other people are developing their own neural network libraries in different languages (see #91). I think it would be useful if we could collect and reference to them e.g. in the readme. This will make it easier for people to find suitable libraries to follow along @shiffman in his tutorials/ coding challenges in their preferred language.