SLING-2993 Add @ConsumerType and @ProviderType annotations as appropriate

- Update to latest BND library dependencies and bundle plugin
- Mark classes (constant and utility classes) not intended to be
  subclassed with JavaDoc.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1516877 13f79535-47bb-0310-9956-ffa450edef68