title: Convert row names into a column in Pandas
body: <p>I have the following Pandas <a href="https://stackoverflow.com/a/25445214/1380929">data frame</a>:</p>
  
  <pre><code>print(df)
  
       head1  head2  head3
  bar     32      3    100
  bix     22    NaN    NaN
  foo     11      1    NaN
  qux    NaN     10    NaN
  xoo    NaN      2     20
  </code></pre>
  
  <p>What I want to do is to convert the row names <code>bar, bix, ...</code> into columns such that 
  in the end I have something like this:</p>
  
  <pre><code>    newhead     head1  head2  head3
  0   bar         32      3    100
  1   bix         22    NaN    NaN
  2   foo         11      1    NaN
  3   qux         NaN    10    NaN
  4   xoo         NaN     2     20
  </code></pre>
  
  <p>How can I achieve that?</p>