Properly convert between JS dates and Cocoa dates.

JS dates are milliseconds since epoch, while Cocoa dates are seconds since epoch.

MEUtils.m

@@ -54,7 +54,7 @@ +(NSObject *)objectFromBsonIterator:(bson_iterator *)it {
 
     case bson_date:
     case bson_timestamp:
-      return [NSDate dateWithTimeIntervalSince1970:bson_iterator_date(it)];
+      return [NSDate dateWithTimeIntervalSince1970:bson_iterator_date(it) / 1000L];
 
     default:
       NSLog(@"MEUtils does not handle type %d", bson_iterator_type(it));