title: Unable to update issue description field size limit in redmine
body: <p>I'm a Redmine administrator, using Redmine 2.2.0. </p>
  
  <p>In projects there is a tab named issues, which has a issue description field. I'm only able to add 645 lines into the issue description field. But I need to add more lines. </p>
  
  <p>Is it a bug of Redmine? Does anyone know how to increase the size of the field? Which ruby file do I need to edit?</p>
  
  <p>Thank you in advance.</p>