Delete log4j-osgi module.

  - Pretty useless module.
  - Will most likely be splitting out some of these modules from log4j-core due to dependencies instead.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1590201 13f79535-47bb-0310-9956-ffa450edef68