Upgrade to Logback 1.1.9

Closes gh-69

spring-boot-dependencies/pom.xml

@@ -124,7 +124,7 @@
 		<junit.version>4.12</junit.version>
 		<liquibase.version>3.5.3</liquibase.version>
 		<log4j2.version>2.6.2</log4j2.version>
-		<logback.version>1.1.8</logback.version>
+		<logback.version>1.1.9</logback.version>
 		<lombok.version>1.16.12</lombok.version>
 		<mariadb.version>1.4.6</mariadb.version>
 		<mockito.version>1.10.19</mockito.version>