adding an isArguments checker and enabling iteration (using each) over JS object hashes that have numeric length properties

test/collections.js

@@ -29,6 +29,10 @@ $(document).ready(function() {
     answer = null;
     _.each([1, 2, 3], function(num, index, arr){ if (_.include(arr, num)) answer = true; });
     ok(answer, 'can reference the original collection from inside the iterator');
+
+    answers = [];
+    _.each({range : 1, speed : 2, length : 3}, function(v){ answers.push(v); });
+    ok(answers.join(', '), '1, 2, 3', 'can iterate over objects with numeric length properties');
   });
 
   test('collections: map', function() {