SLF4J , Simple Logging Facade for Java#

website JIRA issue 376

Steps#

1. run the slf4j migrator
2. add the slf4j-api.jar to the eclipse buildpath
3. src change: log.fatal( ==> log.error(
4. src change: slf4j log methods only accept Strings, so log.error(Exception) ==> log.error(Exception.toString())
5. PropertyConfigurator.configure(props) all over the place (mostly in tests) ==> move log4j stmts from jspwiki.properties to separate log4j.properties (in classpath) ?
6. NDC => MDC ?
7. change build.xml so that slf4j-api.jar is added to WEB-INF/lib
8. test with tomcat
9. test with WebSphere (old JSPWiki version and new (slf4j) JSPWiki version