title: PHPExcel Read datetime as string using rangeToArray()
body: <p>I am using PHPExcel 1.7.7 to read excel file. I encounter a problem similar to this <a href="https://stackoverflow.com/questions/8583915/phpexcel-read-all-values-date-time-numbers-as-strings">thread</a></p>
  
  <p>To get all cell data, I am using rangeToArray() like below:</p>
  
  <p><code> 
  $dataCr = $objWorksheet->rangeToArray('A'.$row.':'.'G'.$row, null, TRUE, TRUE, false);
  </code></p>
  
  <p>However, it didn't return the data in any expected format, such as "2011-01-14 16:15:00" or "2011-01-14" or "2011-02-25 16:15". Instead it returned something like "40599.677083333" or "40599". </p>
  
  <p>I am sure I set both true for the following parameters when using rangeToArray():</p>
  
  <p><code>
  @param  boolean  $calculateFormulas  Should formulas be calculated?
  @param  boolean  $formatData         Should formatting be applied to cell values?
  </code></p>
  
  <p>I also tried update PHPExcel to 1.7.8. didn't work either. Is there way can work around? The expected date could be in different formats as listed above.</p>
  
  <p>Many thanks</p>