title: How to change Date Format in python
body: <p>I have 2 date type in one of python dataframe column, i want to all the data values into same format.</p>
  
  <pre><code>df = pd.DataFrame({'Date':['2016-06-01', '2016-06-01 10:00']})
  print (df)
             Date
  0        2016-06-01
  1  2016-06-01 10:00
  </code></pre>
  
  <p>I want both the date in same format as below.</p>
  
  <pre><code>          Date
  0  2016-06-01 00:00
  1  2016-06-01 10:00
  </code></pre>
  
  <p>how to handle it using python.</p>
  
  <p>Thanks</p>