title: save and retrieve df as .csv without losing type information
body: <p>When I save a <code>pandas.DataFrame</code> to a <code>.csv</code> file, a column of <code>dicts</code> is converted to literal strings.  How can I save/load a df to <code>.csv</code> so that they are equivalent?  I know about pickle, hdf5, etc; I'd like to keep it human readable, but I'm open to alternatives if this is barking up the wrong tree...</p>
  
  <pre><code>df = pd.DataFrame.from_items([('A', [1, 2, {3:30}]), ('B', [4, 5, {6:60}])],
   orient='index', columns=['one', 'two', 'three'])
  
  df.to_csv('test.csv', sep='\t')
  df_loaded = pd.read_csv('test.csv', sep='\t', index_col=0)
  df == df_loaded
  
  """
  output:
  
      one   two  three
  A  True  True  False
  B  True  True  False
  """
  </code></pre>