human readable time representation for toString

Example:
 LinkEvent{time=2014-10-28T23:24:23.461, ...

Change-Id: I439cea488afd97dfa4f1c1e5770f2e2d7b64d321
diff --git a/pom.xml b/pom.xml
index 095e40e..83ed0f4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -319,6 +319,11 @@
                 <artifactId>netty-transport-native-epoll</artifactId>
                 <version>${netty4.version}</version>
             </dependency>
+            <dependency>
+                <groupId>joda-time</groupId>
+                <artifactId>joda-time</artifactId>
+                <version>2.5</version>
+            </dependency>
         </dependencies>
     </dependencyManagement>