Bug 569261 - Latest update to Jetty causes missing constraint

Add o.e.jetty.util.ajax to help feature.

Change-Id: Ie8098e70f5861908ea58491d983b0ca651af4b95
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>

features/org.eclipse.help-feature/feature.xml

@@ -188,6 +188,13 @@
          install-size="0"
          version="0.0.0"
          unpack="false"/>
+
+   <plugin
+         id="org.eclipse.jetty.util.ajax"
+         download-size="0"
+         install-size="0"
+         version="0.0.0"
+         unpack="false"/>
 
    <plugin
          id="org.eclipse.core.net"