title: eclipse issue after installing STS plugin (4.7.1)
body: <p>I'm getting the following error :</p>
  
  <pre><code>Problems occurred when invoking code from plug-in: "org.eclipse.jface".
  java.lang.NullPointerException
      at org.eclipse.jst.jee.ui.internal.navigator.web.WebAppProvider.getImage(WebAppProvider.java:99)
      at org.eclipse.jst.jee.ui.internal.navigator.Web25LabelProvider.getImage(Web25LabelProvider.java:47)
  </code></pre>
  
  <p>I've tried removing all eclipse project artifacts, but it didn't help.  Does anyone know a workaround for this issue ?  I'd hate to remove STS.</p>
  
  <p>thanks in advance.</p>