Add 'delegate' Appender to Apache Geode Logger configuration.

Resolves #117.

Author: jxblum

spring-geode-project/spring-geode-starters/spring-geode-starter-logging/src/main/resources/org/springframework/geode/logging/slf4j/logback/logger-include.xml

@@ -3,14 +3,17 @@
 
 	<logger name="com.gemstone.gemfire" level="${spring.boot.data.gemfire.log.level:-INFO}" additivity="false">
 		<appender-ref ref="${spring.geode.logging.appender-ref:-CONSOLE}"/>
+		<appender-ref ref="delegate"/>
 	</logger>
 
 	<logger name="org.apache.geode" level="${spring.boot.data.gemfire.log.level:-INFO}" additivity="false">
 		<appender-ref ref="${spring.geode.logging.appender-ref:-CONSOLE}"/>
+		<appender-ref ref="delegate"/>
 	</logger>
 
 	<logger name="org.jgroups" level="${spring.boot.data.gemfire.jgroups.log.level:-WARN}" additivity="false">
 		<appender-ref ref="${spring.geode.logging.appender-ref:-CONSOLE}"/>
+		<appender-ref ref="delegate"/>
 	</logger>
 
 </included>