Consistently using servlet API 3.1. There was an export of javax.servlet

in the GWT bundles that had version 2.x but was 3.x. The GWT bundles do
not export servlet API anymore, so everything can consistently be on
servlet version 3.1 that is provided by our jetty server.

java/com.sap.sse.security/META-INF/MANIFEST.MF

@@ -17,7 +17,7 @@ Import-Package: com.sap.sse.util,
  org.osgi.util.tracker;version="1.5.1"
 Bundle-ActivationPolicy: lazy
 Bundle-ClassPath: .
-Require-Bundle: javax.servlet;bundle-version="2.5.0",
+Require-Bundle: javax.servlet;bundle-version="3.1.0",
  slf4j.api;bundle-version="1.6.4",
  org.json.simple,
  com.sun.jersey,