title: how set column as date index?
body: <p>My data sets looks like:</p>
  <pre><code>Date        Value
  1/1/1988    0.62
  1/2/1988    0.64
  1/3/1988    0.65
  1/4/1988    0.66
  1/5/1988    0.67
  1/6/1988    0.66
  1/7/1988    0.64
  1/8/1988    0.66
  1/9/1988    0.65
  1/10/1988   0.65
  1/11/1988   0.64
  1/12/1988   0.66
  1/13/1988   0.67
  1/14/1988   0.66
  1/15/1988   0.65
  1/16/1988   0.64
  1/17/1988   0.62
  1/18/1988   0.64
  1/19/1988   0.62
  1/20/1988   0.62
  1/21/1988   0.64
  1/22/1988   0.62
  1/23/1988   0.60
  </code></pre>
  <p>I used this code to read this data:</p>
  <pre><code>df.set_index(df['Date'], drop=False, append=False, inplace=False, verify_integrity=False).drop('Date', 1)
  </code></pre>
  <p>But the problem is the index is not in date format. So the question is how to set this column as date index?</p>