Update copyright year

Author: jingming

pom.xml

@@ -176,7 +176,7 @@
           <use>true</use>
           <windowtitle>Twilio Java</windowtitle>
           <doctitle><![CDATA[<h1>Twilio Java</h1>]]></doctitle>
-          <bottom><![CDATA[<i>Copyright &#169; 2011 Twilio, Inc. All Rights Reserved.</i>]]></bottom>
+          <bottom><![CDATA[<i>Copyright &#169; 2016 Twilio, Inc. All Rights Reserved.</i>]]></bottom>
         </configuration>
       </plugin>