[KARAF-2221] Fix the main jar packaging to avoid using additional packages.
The main problem is that all bundles can see classes included in the main jar, so adding compendium or util classes could be a problem for bundles.

git-svn-id: https://svn.apache.org/repos/asf/karaf/branches/karaf-2.3.x@1456998 13f79535-47bb-0310-9956-ffa450edef68