SLF4J 1.7.30 instead of 1.7.21

SLF4J 1.7.30 instead of 1.7.21: http://www.slf4j.org/news.html

Author: Neustradamus

pom.xml

@@ -10,6 +10,7 @@
 
     <properties>
         <jettyVersion>9.3.10.v20160621</jettyVersion>
+        <slf4j.version>1.7.30</slf4j.version>
     </properties>
 
     <repositories>
@@ -25,12 +26,12 @@
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
-            <version>1.7.21</version>
+            <version>${slf4j.version}</version>
         </dependency>
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-log4j12</artifactId>
-            <version>1.7.21</version>
+            <version>${slf4j.version}</version>
         </dependency>
         <dependency>
             <groupId>org.eclipse.jetty</groupId>