Implement DecisionTreeKernel

[dmi3coder]

Decision tree fits project really well, this will give ability to use partial fit as well if needed

• Create decision tree kernel with ejml
• Setup decision tree based on PredictionSet
• Retrofit to Java 7
• Allow partial fit

https://towardsdatascience.com/decision-tree-in-python-b433ae57fb93
https://machinelearningmastery.com/implement-decision-tree-algorithm-scratch-python/
https://www.geeksforgeeks.org/decision-tree-implementation-python/