title: No StandardScaler class in sklearn.preprocessing
body: <p>I wanted to use the <code>StandardScaler</code> class in the preprocessing package <a href="http://scikit-learn.org/stable/modules/generated/sklearn.preprocessing.StandardScaler.html#sklearn.preprocessing.StandardScaler" rel="nofollow">http://scikit-learn.org/stable/modules/generated/sklearn.preprocessing.StandardScaler.html#sklearn.preprocessing.StandardScaler</a> but I keep getting an <code>AttributeError: 'module' object has no attribute 'StandardScaler'</code> on scikit-learn 0.13</p>
  
  <p><code>preprocessing.__dict__</code> does not show <code>StandardScaler</code>.</p>
  
  <p>I could use the <code>LabelEncoder</code> class in the same package.</p>