Helper class for testing java.util.logging code

[karstenspang]

For my own project mockjdbc, I wrote a small helper class for testing code using java.util.logging with SLF4J Test. It is needed because, contrary to other SLF4J bridges, it is not enough to add jul-to-slf4j to the test classpath.

I thought it better that it was part of SLF4J Test, so it could benefit others.