use require_relative in c_zookeeper, avoid re-requiring zookeeper/constants accidentally
use require_relative in c_zookeeper, avoid re-requiring zookeeper/constants accidentally

zk-ruby/zookeeper,zk-ruby/zookeeper,zk-ruby/zookeeper,songling88/zookeeper,rickypai/zookeeper,rickypai/zookeeper,songling88/zookeeper,rickypai/zookeeper,songling88/zookeeper,songling88/zookeeper,rickypai/zookeeper