Add poll support

lib/blitline.js

@@ -82,4 +82,17 @@ module.exports = function() {
 
   }
 
-};
+    this.poll = function(jobId, callback) {
+        var request = http.get("http://api.blitline.com/poll?job_id="+jobId, function (res) {
+              var body = "";
+              res.on("data", function(data) {
+                body += data;
+              });
+              res.on("end", function() {
+                callback(JSON.parse(body));
+              });                          
+            });  
+  };
+
+
+};