Began zip for Underbar. Still need to pad with 'undefined' but otherwise working.

Author: austentalbot

src/underbar.js

@@ -631,6 +631,18 @@ var _ = {};
   // Example:
   // _.zip(['a','b','c','d'], [1,2,3]) returns [['a',1], ['b',2], ['c',3], ['d',undefined]]
   _.zip = function() {
+    var results=[];
+    var args=Array.prototype.slice.call(arguments);
+    _.each(args, function(arr) {
+      _.each(arr, function(val, index) {
+        if (results[index]===undefined) {
+          results.push([]);
+        }
+        results[index].push(val);
+      });
+    });
+
+    return results;
   };
 
   // Takes a multidimensional array and converts it to a one-dimensional array.