title: False Positive option don't appear on projects
body: <p>I'm using Sonarqube on Ubuntu 12.01 machine. I use Sonar Runner with Jenkins plugin to analyse my code.</p>
  
  <p>The problem came when I execute an analysis for new projects. For example I have saved on Sonar A and B project, if I execute analysis for new C project for this project false positive option don't appear.
  This occurs since I update Sonar to the last version 4.1.2. With projects that have been created with the previous version all works fine.
  Anyone knows what is the problem?
  For my company the possibility of mark errors like false positive is really important.</p>