title: LabelEncoder() won't store parameters?
body: <p><code>LabelEncoder</code> won't "remember" parameters. When I fit and transform data with it then ask for the parameters, all I get is <code>{}</code>. This makes it impossible to re-use the encoder on new data.</p>
  
  <p>Example:</p>
  
  <pre><code>from sklearn.preprocessing import LabelEncoder
  
  encode = LabelEncoder()
  encode.fit_transform(['one', 'two', 'three'])
  print(encode.get_params())
  </code></pre>
  
  <p>Not sure about the intended format, but I expect something like <code>{['one', 0], ['two', 1], ['three', 2]}</code></p>
  
  <p>Actual Result: <code>{}</code></p>
  
  <p>I'm on:</p>
  
  <pre><code>Darwin-16.7.0-x86_64-i386-64bit
  Python 3.6.1 |Anaconda 4.4.0 (x86_64)| (default, May 11 2017, 13:04:09) 
  [GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)]
  NumPy 1.12.1
  SciPy 0.19.0
  Scikit-Learn 0.18.1
  </code></pre>