update to the latest log4j2 version

Author: istvanballok

cf-java-logging-support-log4j2/pom.xml

@@ -15,7 +15,7 @@
 	</parent>
 
 	<properties>
-		<log4j2.version>2.4.1</log4j2.version>
+		<log4j2.version>2.7</log4j2.version>
 	</properties>
 
 	<dependencies>

sample/pom.xml

@@ -12,7 +12,7 @@
 
 	<properties>
 		<tomcat.version>7.0.65</tomcat.version>
-		<log4j2.version>2.4.1</log4j2.version>
+		<log4j2.version>2.7</log4j2.version>
 		<logback.version>1.1.3</logback.version>
 		<jackson.version>2.5.4</jackson.version>
 		<slf4j.version>1.7.12</slf4j.version>