Use Boot’s base Logback configuration in the Integration sample

Fixes #922

spring-boot-samples/spring-boot-sample-integration/src/main/resources/logback.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <configuration>
-	<property name="LOG_PATTERN" value="[%d{yyyy-MM-dd HH:mm:ss.SSS}] - ${PID:-????} %5p [%t] --- %c{1}: %m%n"/>
-	<property name="LOG_FILE" value="${LOG_FILE:-${LOG_PATH:-/tmp/}spring.log}"/>
-	<appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
-		<encoder>
-			<pattern>${LOG_PATTERN}</pattern>
-		</encoder>
-	</appender>
-	<appender name="FILE"
-		class="ch.qos.logback.core.rolling.RollingFileAppender">
-		<encoder>
-			<pattern>${LOG_PATTERN}</pattern>
-		</encoder>
-		<file>${LOG_FILE}</file>
-		<rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
-			<fileNamePattern>${LOG_FILE}.%i</fileNamePattern>
-		</rollingPolicy>
-		<triggeringPolicy
-			class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
-			<MaxFileSize>10MB</MaxFileSize>
-		</triggeringPolicy>
-	</appender>
+	<include resource="org/springframework/boot/logging/logback/base.xml"/>	
+
 	<logger name="org.springframework.integration.file" level="DEBUG" />
-	<root level="INFO">
-		<appender-ref ref="CONSOLE" />
-		<appender-ref ref="FILE" />
-	</root>
-</configuration>
+</configuration>
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