providing additional p6spy-*-nodep.jar build artifacts (wrapping misc slf4j implementations); fixes #131

Just one open point for me here:
In the `com.p6spy.engine.spy.appender.Slf4JLogger` I changed: `log = LoggerFactory.getLogger("p6spy");` to: `log = LoggerFactory.getLogger(Slf4JLogger.class);`

as otherwise package based filtering didn't work for me in the tests (see configs: log4j-in-test-DEBUG.xml, log4j-in-test-INFO.xml, ...)

Still I think I don't completely understand all the consequences this might cause.

Comments welcome.