FELIX-4427 Fix API exports

- Add OSGi Http Service API to API bundle
- Depend on Servlet API 2.3 in the API bundle
  (first Servlet API supporting Filter)
- Remove Servlet and Http Service API exports
  from Jetty bundle


git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1569268 13f79535-47bb-0310-9956-ffa450edef68