[ONOS-3702] Clean up pom.xml dependency, bump up omitted dependency

Change-Id: Ieb6dc7a5b3ee8d52eefd79c182b9d759b5d324d7
diff --git a/pom.xml b/pom.xml
index 15b5407..20d764c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -86,7 +86,7 @@
         <karaf.version>3.0.5</karaf.version>
         <jersey.version>1.19</jersey.version>
         <jackson.version>2.7.0</jackson.version>
-        <slf4j.version>1.7.6</slf4j.version>
+        <slf4j.version>1.7.13</slf4j.version>
         <guava.version>19.0</guava.version>
         <commons.io.version>2.4</commons.io.version>
         <!-- TODO argLine was originally added maven-surfire-plugin configuration