Upgrade logback 1.1.8

Author: slandelle

pom.xml

@@ -380,7 +380,7 @@
 		<target.property>1.8</target.property>
 		<netty.version>4.1.6.Final</netty.version>
 		<slf4j.version>1.7.21</slf4j.version>
-		<logback.version>1.1.7</logback.version>
+		<logback.version>1.1.8</logback.version>
 		<testng.version>6.9.10</testng.version>
 		<jetty.version>9.3.12.v20160915</jetty.version>
 		<tomcat.version>6.0.45</tomcat.version>