3.1 update site fail

Author: jantje

it.baeyens.arduino.updatesite/category.xml

@@ -3,6 +3,9 @@
    <feature url="features/it.baeyens.arduino.feature_3.0.0.qualifier.jar" id="it.baeyens.arduino.feature" version="3.0.0.qualifier">
       <category name="Arduino"/>
    </feature>
+   <feature url="features/it.baeyens.arduino.feature_3.1.0.qualifier.jar" id="it.baeyens.arduino.feature" version="3.1.0.qualifier">
+      <category name="Arduino"/>
+   </feature>
    <category-def name="Arduino" label="Arduino Eclipse Plugin">
       <description>
          Arduino development in the Eclipse IDE.