Add a way to publish a change to a keypath (only goes through when resolvable).

@@ -70,7 +70,7 @@ class Rivets.Binding
       if @view.formatters[id]?.publish
         value = @view.formatters[id].publish value, args...
 
-    @observer.setValue value
+    @observer.publish value
 
   # Subscribes to the model for changes at the specified keypath. Bi-directional
   # routines will also listen for changes on the element to propagate them back

@@ -49,6 +49,10 @@ class Rivets.Observer
   read: (key, obj) =>
     @adapter(key).read obj, key.path
 
+  publish: (value) =>
+    if @target?
+      @adapter(@key).publish @target, @key.path, value
+
   value: =>
     @read @key, @target if @target?