Update zookeeper version and url in travis config

Author: samuel

.travis.yml

@@ -9,7 +9,7 @@ branches:
     - master
 
 before_install:
-  - wget http://apache.claz.org/zookeeper/zookeeper-3.4.6/zookeeper-3.4.6.tar.gz
+  - wget http://apache.cs.utah.edu/zookeeper/zookeeper-3.4.10/zookeeper-3.4.10.tar.gz
   - tar -zxvf zookeeper*tar.gz
   - go get github.com/mattn/goveralls
   - go get golang.org/x/tools/cmd/cover