[logback-dev] Joran tutorial

Hello all, I just added a tutorial on Joran. As you know, Joran is a generic configuration framework. This tutorial does not teach users how to configure logback-classic nor logback-access. It shows developers how to build config systems of their own by extending Joran. Comments/corrections most welcome. -- Ceki Gülcü Logback: The reliable, generic, fast and flexible logging framework for Java. http://logback.qos.ch