Squelch logging by org.apache.storm.zookeeper.server.NIOServerCnxnFac…

…tory in tests

Storm 0.9.3 relocates/shades org.apache.zookeeper to org.apache.storm.zookeeper; cf.
`storm-core/pom.xml` in Storm's code repository:

    <relocation>
        <pattern>org.apache.zookeeper</pattern>
        <shadedPattern>org.apache.storm.zookeeper</shadedPattern>
    </relocation>

src/test/resources/logback-test.xml

@@ -97,5 +97,9 @@
     <level value="OFF"/>
     <appender-ref ref="ACCESS"/>
   </logger>
+  <logger name="org.apache.storm.zookeeper.server.NIOServerCnxnFactory" additivity="false" >
+    <level value="OFF"/>
+    <appender-ref ref="ACCESS"/>
+  </logger>
 
 </configuration>