Merge pull request #3 from Vadskye/master

Added my decision tree code for potential use as a base
added a new function to count the number of nodes in a tree, a different function to prune the tree, and fixed the function to get the features used in a tree
Merge branch 'master' of https://github.com/timothyb0912/cs289_final_project
demo of pruning function in treepredict.py
the pruned tree based on the 2011 training set
Merge remote-tracking branch 'upstream/master'