Bootstrap listener for custom Logback initialization in a web environment.
Delegates to WebLogbackConfigurer (see its javadoc for configuration details).
WARNING: Assumes an expanded WAR file, both for loading the configuration
file and for writing the log files. If you want to keep your WAR unexpanded or
don't need application-specific log files within the WAR directory, don't use
Logback setup within the application (thus, don't use Log4jConfigListener or
LogbackConfigServlet). Instead, use a global, VM-wide Log4J setup (for example,
in JBoss) or JDK 1.4's
java.util.logging (which is global too).
This listener should be registered before ContextLoaderListener in web.xml,
when using custom Logback initialization.
For Servlet 2.2 containers and Servlet 2.3 ones that do not initialize listeners before servlets, use
LogbackConfigServlet. See the ContextLoaderServlet javadoc for details.