Add update functions on both Rivets.View and Rivets.Binding used for updating bi…

…ndings with a new set of models. [Closes #131]

@@ -123,6 +123,13 @@ class Rivets.Binding
 
         @view.config.adapter.unsubscribe model, keypath, @sync
 
+  # Updates the binding's model from what is currently set on the view. Unbinds
+  # the old model first and then re-binds with the new model.
+  update: =>
+    @unbind()
+    @model = @view.models[@key]
+    @bind()
+
 # A collection of bindings built from a set of parent elements.
 class Rivets.View
   # The DOM elements and the model objects for binding are passed into the
@@ -222,6 +229,12 @@ class Rivets.View
   publish: =>
     binding.publish() for binding in @select (b) -> b.binder.publishes
 
+  # Updates the view's models along with any affected bindings.
+  update: (models = {}) =>
+    for key, model of models
+      @models[key] = model
+      binding.update() for binding in @select (b) -> b.key is key
+
 # Cross-browser event binding.
 bindEvent = (el, event, handler, context) ->
   fn = (e) -> handler.call context, e