Refactor and encapsulate Properties, Logger and Appender SLF4J Logback configuration (metadata) in separate includes (XML files) on the application classpath.

Resolves #117.

Author: jxblum

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

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<included>
+
+	<if condition='property("bootPresent").equals("false")'>
+		<then>
+			<appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
+				<encoder>
+					<charset>${SPRING_BOOT_LOG_CHARSET}</charset>
+					<pattern>${SPRING_BOOT_LOG_PATTERN}</pattern>
+				</encoder>
+			</appender>
+		</then>
+	</if>
+
+	<appender name="delegate" class="org.springframework.geode.logging.slf4j.logback.DelegatingAppender"/>
+
+	<appender name="geode" class="ch.qos.logback.core.ConsoleAppender">
+		<encoder>
+			<charset>${APACHE_GEODE_LOG_CHARSET}</charset>
+			<pattern>${APACHE_GEODE_LOG_PATTERN}</pattern>
+		</encoder>
+	</appender>
+
+</included>

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

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<included>
+
+	<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>

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

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<included>
+
+	<property name="SPRING_BOOT_LOG_CHARSET" value="${SPRING_BOOT_LOG_CHARSET:-${file.encoding:-UTF-8}}"/>
+	<property name="SPRING_BOOT_LOG_PATTERN" value="${SPRING_BOOT_LOG_PATTERN:-%d %5p %40.40c:%4L - %msg%n}"/>
+	<property name="APACHE_GEODE_LOG_CHARSET" value="${APACHE_GEODE_LOG_CHARSET:-${file.encoding:-UTF-8}}"/>
+	<property name="APACHE_GEODE_LOG_PATTERN" value="${APACHE_GEODE_LOG_PATTERN:-[%level{lowerCase=true} %date{yyyy/MM/dd HH:mm:ss.SSS z} &lt;%thread&gt;] %message%n%throwable%n}"/>
+
+</included>