Support for apache juli logging (juli-over-slf4j)

I created the juli-over-slf4j by adapting the source code from jcl-over-slf4.

Although it is possible to use the jcl-over-slf4 adapter together with the commons-logging adapter, this means a unnecessary double indirection.

My main motivation is to use the tomcat-jdbc-pool without tomcat, but with slf4j instead of juli and commons-logging.