Add support for passing String parameters to helper

lib/handlebars/ast.js

@@ -60,7 +60,7 @@ var Handlebars = require("handlebars");
 
   Handlebars.AST.IdNode = function(parts) {
     this.type = "ID";
-    this.original = parts.join("/");
+    this.original = parts.join(".");
 
     var dig = [], depth = 0;
 
@@ -73,6 +73,7 @@ var Handlebars = require("handlebars");
     }
 
     this.parts    = dig;
+    this.string   = dig.join('.');
     this.depth    = depth;
     this.isSimple = (dig.length === 1) && (depth === 0);
   };