Create DecisionTree.py

This is a Python script designed to build, but not graph,
a decision tree from a dataset.

The code will enter through createTree(). From there, some basic stopping functions
will be tested using majorityCount(). If the stopping assumptions aren't met, then
createTree() will chooseBestFeatureToSplit(), and recursively call itself until the
stopping conditions are met.

This is the structure of the following script:

---Supervised Training---
-createTree()
    >>majorityCount()
    >>chooseBestFeatureToSplit()
        >splitDataSet()
        >calculateShannonCoef()


---Classification---
-classify()