title: Reset column index of pandas dataframe
body: <p>Is it possible to reset columns so they becomes first row of <code>DataFrame</code>. For example,</p>
  
  <pre><code>import pandas as pd
  
  df = pd.DataFrame({'a': [1, 2, 3], 'b': [4, 5, 6]})
     a  b
  0  1  4
  1  2  5
  2  3  6
  </code></pre>
  
  <p>Desired ouput, </p>
  
  <pre><code>df2 = df.reset_column() ???
     0  1
  0  a  b
  1  1  4
  2  2  5
  3  3  6
  </code></pre>