title: Convert a series of string to date
body: <p>I have the data like this</p>
  
  <p><code>df['Date']=['05.01.2017','05.01.2017']</code></p>
  
  <p>I tried </p>
  
  <p><code>df1= pd.to_datetime(df['Date'])</code></p>
  
  <p>but it turned a bad result </p>
  
  <p>Id like to get the new data like this</p>
  
  <p><code>result=[05-01-2017,05-01-2017]</code></p>