change EVENT_TYPE_NAMES and STATE_NAMES values to strings
change EVENT_TYPE_NAMES and STATE_NAMES values to strings

clean up nasty implementation of event_by_value and state_by_value

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