The log4j2.xml file needs to be in the classpath. Is it located under WEB-INF/classes? Also, do you have both the log4j-core-2.0 and log4j-api-2.0 jar files in the classpath (WEB-INF/lib)? You need both these jars.
Your configuration looks correct. You can try setting <Configuration status="trace">
in the first line of the config to get log4j2-internal debug log messages on the console. This may help track down configuration problems.