title: force format when parsing dates in pandas from an Excel file
body: <p>I am trying to parse dates from an Excel file following a given format <code>%d/%m/%y</code>. I am not able to set the format, I am always getting <code>%m/%d/%Y</code>.</p>
  
  <p>The source format is <code>%d/%m/%y</code> so that the first date should be first of June 2016. Any ideas on how to do it?</p>
  
  <pre><code>import pandas as pd
  
  url = 'https://www.dropbox.com/s/8gqmq3jx27unsta/example_dates.xlsx?dl=1'
  
  file = pd.ExcelFile(url, parse_date=True, 
         date_parser = (lambda x: pd.to_datetime(x, format ='%d/%m/%y')))
  
  df = file.parse(0)
  
  df
      date    variable
  0   2016-01-06  1
  1   2016-06-07  2
  2   2016-12-10  3
  3   2016-12-29  4
  </code></pre>
  
  <p>Something like this might work but it doesn't:</p>
  
  <pre><code>df = file.parse(0, converters={'date' : lambda x: pd.to_datetime(x, dayfirst=True)}
  
  date    variable
  0   2016-01-06  1
  1   2016-06-07  2
  2   2016-12-10  3
  3   2016-12-29  4
  </code></pre>