Disable Javadoc lint

mvn site running on Java 8 complains about thousands of missing
@return tags among other things.
diff --git a/project/pom.xml b/project/pom.xml
index e152285..6a4c6c3 100644
--- a/project/pom.xml
+++ b/project/pom.xml
@@ -1120,6 +1120,7 @@
             <links>
               <link>http://download.oracle.com/javase/6/docs/api/</link>
             </links>
+            <additionalJOption>-Xdoclint:none</additionalJOption>
           </configuration>
         </plugin>
       </plugins>