[WFLY-2995] When properties change on log4j appenders activate should be invoked

The ```activate()``` method on the ```Log4jAppenderHandler``` was only getting invoked when a handler was added. This creates a problem when the user changes a property, such as a file, the property value is changed, but the appender might not set the output stream. Since the properties are set on a ```PojoConfiguration``` and the ```activate``` method is on the ```HandlerConfiguration``` the method was never invoked on property changes. This simply adds a dummy property to be changed on the handler which will invoke the activation method.

Also a simple change to set the name on the appender.