Refactor logging dependencies for SBDG Starters Gradle build files.

Remove the exclude on 'org.apache.logging.log4j:log4j-to-slf4j'.

Add an exclude on 'org.apache.logging.log4j:log4j-core'.

Resolves gh-42.

spring-gemfire-starter-session/spring-gemfire-starter-session.gradle

@@ -7,6 +7,8 @@ dependencies {
 
     compile(project(':spring-gemfire-starter'))
 
-    compile 'org.springframework.session:spring-session-data-gemfire'
+    compile('org.springframework.session:spring-session-data-gemfire') {
+        exclude group: "org.apache.logging.log4j", module: "log4j-core"
+    }
 
 }

spring-gemfire-starter-test/spring-gemfire-starter-test.gradle

@@ -5,12 +5,12 @@ description = "Spring Boot Test Starter for Pivotal GemFire"
 
 dependencies {
 
-	compile("org.springframework.boot:spring-boot-starter-test") {
+	compile "org.springframework.boot:spring-boot-starter-test"
-		exclude group: "org.apache.logging.log4j", module: "log4j-to-slf4j"
-	}
 
 	compile(project(':spring-gemfire-starter'));
 
-	testCompile "org.springframework.data:spring-data-gemfire-test:$springDataGeodeTestVersion"
+	testCompile("org.springframework.data:spring-data-gemfire-test:$springDataGeodeTestVersion") {
+		exclude group: "org.apache.logging.log4j", module: "log4j-core"
+	}
 
 }

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

@@ -5,9 +5,7 @@ description = "Spring Boot Starter for Pivotal GemFire"
 
 dependencies {
 
-	compile("org.springframework.boot:spring-boot-starter") {
+	compile "org.springframework.boot:spring-boot-starter"
-		exclude group: "org.apache.logging.log4j", module: "log4j-to-slf4j"
-	}
 
 	compile(project(':spring-geode')) {
 		exclude group: "org.springframework.data", module: "spring-data-geode"
@@ -17,10 +15,11 @@ dependencies {
 		exclude group: "org.springframework.data", module: "spring-data-geode"
 	}
 
-	compile "org.springframework.data:spring-data-gemfire"
+	compile("org.springframework.data:spring-data-gemfire") {
+		exclude group: "org.apache.logging.log4j", module: "log4j-core"
+	}
 
 	runtime 'javax.cache:cache-api'
-
 	runtime 'org.springframework.shell:spring-shell'
 
 }

spring-geode-starter-session/spring-geode-starter-session.gradle

@@ -7,6 +7,8 @@ dependencies {
 
     compile(project(':spring-geode-starter'))
 
-    compile 'org.springframework.session:spring-session-data-geode'
+    compile('org.springframework.session:spring-session-data-geode') {
+        exclude group: "org.apache.logging.log4j", module: "log4j-core"
+    }
 
 }

spring-geode-starter-test/spring-geode-starter-test.gradle

@@ -5,12 +5,12 @@ description = "Spring Boot Test Starter for Apache Geode"
 
 dependencies {
 
-	compile("org.springframework.boot:spring-boot-starter-test") {
+	compile "org.springframework.boot:spring-boot-starter-test"
-		exclude group: "org.apache.logging.log4j", module: "log4j-to-slf4j"
-	}
 
 	compile(project(':spring-geode-starter'))
 
-	testCompile 'org.springframework.data:spring-data-geode-test'
+	testCompile('org.springframework.data:spring-data-geode-test') {
+		exclude group: "org.apache.logging.log4j", module: "log4j-core"
+	}
 
 }

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

@@ -5,16 +5,12 @@ description = "Spring Boot Starter for Apache Geode"
 
 dependencies {
 
-	compile("org.springframework.boot:spring-boot-starter") {
+	compile "org.springframework.boot:spring-boot-starter"
-		exclude group: "org.apache.logging.log4j", module: "log4j-to-slf4j"
-	}
 
 	compile(project(':spring-geode'))
-
 	compile(project(':spring-geode-autoconfigure'))
 
 	runtime 'javax.cache:cache-api'
-
 	runtime 'org.springframework.shell:spring-shell'
 
 }