Allow binders to specify a 'tokenizes' flag; when true, rivets will do

nothing at all with keypath, and it look into the model at all to fetch
the value.  It will not do any change support for the keypath either.
This allows the binder to do something completely different with the
attribute value.  This can be access by way of this.keypath.

@@ -82,6 +82,7 @@ class Rivets.Binding
 
   # Publishes the value currently set on the input element back to the model.
   publish: => 
+    return if @binder.tokenizes
     value = getInputValue @el
 
     for formatter in @formatters.slice(0).reverse()
@@ -103,7 +104,7 @@ class Rivets.Binding
     if @options.bypass
       @sync()
     else
-      Rivets.config.adapter.subscribe @model, @keypath, @sync if @keypath
+      Rivets.config.adapter.subscribe @model, @keypath, @sync if @keypath and !@binder.tokenizes
       @sync() if Rivets.config.preloadData
 
     loopDeps @, (model, keypath) => Rivets.config.adapter.subscribe model, keypath, @sync
@@ -112,7 +113,7 @@ class Rivets.Binding
   unbind: =>
     @binder.unbind?.call @, @el
 
-    unless @options.bypass
+    unless @options.bypass or !@binder.tokenizes
       Rivets.config.adapter.unsubscribe @model, @keypath, @sync if @keypath
 
     loopDeps @, (model, keypath) => Rivets.config.adapter.unsubscribe model, keypath, @sync
@@ -187,18 +188,20 @@ defaultExpressionParser = (view, node, type, models, value) ->
     bypass: path.indexOf(':') != -1
     bindContext: models
   parsingSupport = Rivets.config.adapter.parsingSupport
-  [options.binder, options.args] = findBinder type
-  firstPart = if parsingSupport
+  [binder, options.args] = findBinder type
+  binderTokenizes = binder.tokenizes
+  options.binder = binder
+  firstPart = if parsingSupport or binderTokenizes
     splitPath[0]
   else
     splitPath.shift()
-  model = if firstPart
+  model = if firstPart or !binderTokenizes
     Rivets.config.adapter.read models, firstPart
   else
     models
   keypath = splitPath.join '.'
 
-  if model
+  if model or binderTokenizes
     if dependencies = context.shift()
       options.dependencies = dependencies.split /\s+/