title: openpyxl - comment.author not visible in xlsx file
body: <p>Usually when you write a comment in Excel it highlights the author name and then starts the actual comment for a cell.</p>
  
  <p>But, when i try creating a comment with openpyxl, the Author name is not visible.</p>
  
  <pre><code>comment_copy = openpyxl.comments.Comment(text='blah',author='someone')
  ws["A3"].comment = comment_copy
  </code></pre>
  
  <p>The resulting comment in the xlsx file only has the value "blah" in cell A3 ( No Author name)</p>
  
  <p>What am i doing wrong ?</p>
  
  <p>Thanks</p>