Add new 'spring-geode-starter-logging' and 'spring-gemfire-starter-logging' modules.

The new modules enable logging output to be rendered for both Apache Geode & Pivotal GemFire given the right configuration now that the SDG @EnableLogging annotaiton is effectively deprecated since the corresponding GemFire/Geode properties (i.e. gemfire.log-level) no longer have any effect.

Resolves gh-73.

settings.gradle

@@ -32,4 +32,5 @@ buildFiles.each { File buildFile ->
 		project.buildFileName = buildFile.name
 	}
 }
+include 'spring-gemfire-starter-logging'
 

spring-gemfire-starter-logging/spring-gemfire-starter-logging.gradle

@@ -0,0 +1,10 @@
+apply plugin: 'io.spring.convention.spring-module'
+apply from: MAVEN_POM_EDITOR_GRADLE
+
+description = "Spring Boot Logging Starter for Pivotal GemFire with Logback as the logging provider and adaptation of Log4j to SLF4J"
+
+dependencies {
+
+    compile project(":spring-geode-starter-logging")
+
+}

spring-geode-starter-logging/spring-geode-starter-logging.gradle

@@ -0,0 +1,11 @@
+apply plugin: 'io.spring.convention.spring-module'
+apply from: MAVEN_POM_EDITOR_GRADLE
+
+description = "Spring Boot Logging Starter for Apache Geode with Logback as the logging provider and adaptation of Log4j to SLF4J"
+
+dependencies {
+
+    compile "org.apache.logging.log4j:log4j-to-slf4j"
+    compile "org.springframework.boot:spring-boot-starter-logging"
+
+}

spring-geode-starter-logging/src/main/resources/logback.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration debug="false">
+
+	<statusListener class="ch.qos.logback.core.status.NopStatusListener"/>
+
+	<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
+		<encoder>
+			<pattern>%d %5p %40.40c:%4L - %m%n</pattern>
+		</encoder>
+	</appender>
+
+	<logger name="com.gemstone.gemfire" level="${spring.boot.data.gemfire.log.level:-INFO}" additivity="false"/>
+	<logger name="org.apache.geode" level="${spring.boot.data.gemfire.log.level:-INFO}" additivity="false"/>
+	<logger name="org.jgroups" level="${spring.boot.data.gemfire.jgroups.log.level:-ERROR}" additivity="false"/>
+
+	<root level="${logback.root.log.level:-ERROR}">
+		<appender-ref ref="console"/>
+	</root>
+
+</configuration>