added polling_stream to event api

lib/api/event.js

@@ -57,6 +57,25 @@ event_api.prototype.stream = function(start, end, filter, callback){
     this.request('GET', '/events', params, callback);
 };
 
+event_api.prototype.polling_stream = function(interval, filter, callback){
+    if(arguments.length < 3 && v8type.is(arguments[1], v8type.FUNCTION)){
+	callback = arguments[1];
+	filter = {};
+    }
+    if(!v8type.is(filter, v8type.OBJECT)){
+	throw new Error('`filter` parameter must be an object');
+    }
+
+    var last_run = new Date().getTime() / 1000;
+    var self = this;
+    setInterval(function(){
+	var start = last_run;
+	var end = last_run = new Date().getTime() / 1000;
+	self.stream(start, end, filter, callback);
+    }, interval * 1000);
+
+};
+
 event_api.prototype.get_event = function(event_id, callback){
     /*
      * event_api.get_event(event_id, callback)