LPS-41264  portal log4j levels for plugins

From Joseph: 

I found some time and implemented this feature -- each plugin developer will be able to say, that he wants to set some categories to certain levels in descriptor of the plugin, after his plugin is deployed. So he might set DEBUG folfall his classes tath use LogFactoryUtil.getLog(), without the need to go to Control Panel each time he restarts the server (or having to do this in EXT).

Would be also cool, if the logging levels could be set per-plugin (in CP / plugin descriptor), so e.g. org.springframework will have DEBUG only in my plugin classes, but not in the whole portal. But that's completely another story :-)

Thanks,