add before_render and after_render methods

[catmando]

before_render works just like before_mount + before_update

likewise for after_render

Useful in cases where you need the same executed both before mounting and before updating.

[catmando]

closed. see hyper-component/spec/client_features/component_spec.rb it 'has a before_render method that is called before_mount and before_update' for example