In Binding.formattedValue, do not directly access the model; use

adapter.read instead.  This broke 1 test case.  Going forward,
adapter.read *must* do something sensible, at the least doing an
object[key].

@@ -6,7 +6,7 @@ describe('Rivets.Binding', function() {
       adapter: {
         subscribe: function() {},
         unsubscribe: function() {},
-        read: function() {},
+        read: function(model, key) { return model[key]; },
         publish: function() {}
       }
     });

@@ -41,8 +41,9 @@ class Rivets.Binding
       args = formatter.split /\s+/
       id = args.shift()
 
-      formatter = if model[id] instanceof Function
-        model[id]
+      m = Rivets.config.adapter.read model, id
+      formatter = if m instanceof Function
+        m
       else
         Rivets.formatters[id]