replace log4j2.properties with log4j2.xml

The properties support for log4j2 is not well documented and
possibly buggy. I couldn't figure out how to change the log
level of a logger.

pdb-ui/src/main/resources/log4j2.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration>
+  <Appenders>
+    <Console name="Console" target="SYSTEM_OUT">
+      <PatternLayout pattern="%d %5p [%-20.20t] %-30.30c{1.} : %m%n"/>
+    </Console>
+  </Appenders>
+  <Loggers>
+    <Root level="INFO">
+      <AppenderRef ref="Console"/>
+    </Root>
+    <!-- 
+    	An example of how to reconfigure the log level for a logger.
+    	This example is a no-op.
+     -->
+  	<logger name="org.lucares.performance.db" level="INFO" additivity="false">
+  		<AppenderRef ref="Console"/>
+  	</logger>
+  </Loggers>
+</Configuration>