Add resource loader abstraction.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1590352 13f79535-47bb-0310-9956-ffa450edef68
Add osgi package.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1590353 13f79535-47bb-0310-9956-ffa450edef68