Add package-info.java file for JavaDoc

Requires Java 5+ JDK to build. Deployment on Java 1.4 platforms
is still available since the classes are in Java 1.4 class file
format.

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1484782 13f79535-47bb-0310-9956-ffa450edef68