Update travis.yml to auto-publish javadoc & jdiff on changes, update javadoc/jdiff scripts to make it work.
diff --git a/.travis.yml b/.travis.yml
index 7a1b208..35d46b7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,6 +21,8 @@
   email:
     recipients:
       - google-guice-dev+ci@googlegroups.com
+
+secure: "fiX80bwvhhtfngYi8F2Z6D9Umbpcmmws0uZK8/Y/2eR7GOOh8qffqeA7vtqsnZJEMy1F6Hpls1BKmOwJCiNFLnBWkkJ8noCd2xK23cZSd63ZKCSis9jVdeiRh+0Cn/8ksouc571Kfp6XgSjW/cKdVlw4NYaIaEsWyovsAwTqO7A="
  
 branches:
   only: