text: Title: Classifier Evaluation in Examples Notebook
  Body: Classifier Evaluation imports in `examples.ipynb`: `from sklearn.cross_validation import train_test_split` has been deprecated and issues a warning.
  
  ### Proposal/Issue
  
  Update `import sklearn.cross_validation` to `import sklearn.model_selection`
  
  Will remove warning: 
  
  ```
  /usr/local/lib/python3.6/site-packages/sklearn/cross_validation.py:44: DeprecationWarning: This module was deprecated in version 0.18 in favor of the model_selection module into which all the refactored classes and functions are moved. Also note that the interface of the new CV iterators are different from that of this module. This module will be removed in 0.20.
    "This module will be removed in 0.20.", DeprecationWarning)
  ```
  
  ### Code Snippet
  
  ```python
  from sklearn.naive_bayes import GaussianNB
  from sklearn.linear_model import LogisticRegression 
  from sklearn.ensemble import RandomForestClassifier
  from sklearn.cross_validation import train_test_split
  ```