Upgrade logback steno. (#26)

Author: vjkoskela

pom.xml

@@ -91,7 +91,7 @@
     <junit.benchmarks.version>0.7.2</junit.benchmarks.version>
     <junit.version>4.12</junit.version>
     <logback.version>1.1.3</logback.version>
-    <logback.steno.version>1.13.0</logback.steno.version>
+    <logback.steno.version>1.16.0</logback.steno.version>
     <log4j.over.slf4j.version>1.7.12</log4j.over.slf4j.version>
     <metrics.aggregator.protocol.version>1.0.3</metrics.aggregator.protocol.version>
     <metrics.client.version>0.4.5</metrics.client.version>