title: sonar .net plugin fails for mixed languages
body: <p>I am trying to run Sonar on a .net solution,
  which contains mainly c# projects, with one legacy vb.net project.
  Sonar fails to run with this error message:</p>
  
  <p><strong>Language with key 'vbnet' not found.</strong></p>
  
  <p>I've tried to exclude the project in the config file using:
  <strong>sonar.skippedModules</strong>  , but that didn't help.</p>
  
  <p>The only solution I've found so far is the Vb.Net <a href="http://www.sonarsource.com/products/plugins/languages/vb-net/" rel="nofollow">plugin</a>, 
  which costs a LOT of money.</p>
  
  <p>Would appreciate any help in resolving/working around this issue.</p>
  
  <p>Thanks,
  Omer</p>