Stop a bunch of test dependencies from being exported as real dependencies

Cannot start server with pac4j on classpath due to java.lang.IllegalStateException: Detected both log4j-over-slf4j.jar AND slf4j-log4j12.jar on the class path, preempting StackOverflowError. See also http://www.slf4j.org/codes.html#log4jDelegationLoop for more details.
Yes, but this dependency (the packaged tests of pac4j-core) is already marked as a ```test``` dependency in the main pom.xml: https://github.com/leleuj/pac4j/blob/master/pom.xml#L84.