Provide option for Spring Roo managed XML configuration for Services, Controllers, GWT Locators, etc.

For some environments, notably GAE, it is preferable to use XML configuration instead of annotations. Doing so reduces the amount of time required for applications to start up. In an environment like GAE where applications are frequently created and destroyed, using XML configuration can greatly increase performance. See https://developers.google.com/appengine/articles/spring_optimization