title: phpexcel class adding single inverted comma in datetime field
body: <p>I am using phpexcel class for adding my data to excel.</p>
  
  <p>My field is 2015-05-05 34:23:45 it shows '2015-05-05 34:23:45 in excel.</p>
  
  <p>Can anyone have idea, why ? All cell data showing perfect while echo. but when writes to excel it adds single inverted comma.</p>
  
  <p>Can anyone have idea, why ?</p>
  
  <p>Thanks in advance.</p>