Default "org.osgi.framework.system.packages.extra" configuration should be empty

Karaf's default configuration for org.osgi.framework.system.packages.extra should be empty and available for use solely by end user applications. Currently (6.2.1) the default configuration for this property is populated with a long list of packages which must be replicated and added to by end user applications in order to expose any additional library packages through the OSGi system bundle. Since the packages currently specified are always required by the JBoss Fuse runtime it would make better sense to move them to the configuration of the org.osgi.framework.system.packages property instead.