Generate and publish a "testlib" artifact in libraft-core

[allengeorge]

libraft-core defines a class called TestLoggingRule that is used in both libraft-agent and kayvee. It would be ideal for libraft-core to define a separate artifact called libraft-core-testlib that is published to maven along with the other artifacts. While I'm able to generate this, I can't publish it because the publishing task in gradle 1.8 fails with an error. Either I'm using the task wrong, or the task itself is incomplete. Either way, my current workaround is to simply create copies of that rule in the other sub-projects, which is not ideal. The build should be fixed so that a separate libraft-core-testlib jar, sources.jar and javadoc.jar is built and published to maven central.