anchor.diff:  An asset object is required to have the following attributes:
   
   . +root+
  -* The asset root, provided to the content provider.
  +* The asset root, provided to the asset class.
   * This folder should be specified relative to the project root.
   * Filenames specified in input objects should be relative to this directory,
   in the interest of convention.
  
positive.code: 
  In addition there is a +dist+ attribute. It specifies the root of the
  distribution folder relative to the project root. If not provided the default
  value is +dist/+.
  
  [source,json]
  ----
  
negative.code: 
  == How do I extend it?
  
  Easy, open up a Python class like this and implement the following:
  
  [source,python]
  ----
  class MyAsset(BaseAsset):
      def list_output(self):
          pass
      def install(self, filename):
          pass
      def validate(self, input_obj):
          pass
  ----
  
  Better yet, inherit from +StaticAsset+ to get a +list_output+
  implementation that handles file and directory inputs (a directory input is
  equivalent to adding it's contents recursively.) and a +validate+
  implementation that asserts the input is a pathname pointing to an existing
  file.
  
  [source,python]
  ----
  class MyStaticAsset(StaticContentProvier):
      def install(self, filename):
        pass
  ----
  
  