Implemented tests for Container classes.

- Added Peach_Markup_ContainerTestImpl
- Implemented tests using ContainerTestImpl
Modified Peach_Markup_NodeList

- Fixed comments
- Removed appendNode (Integrated with 'append')
Modified comments for Peach_Markup_Container.
Added Peach_Markup_NoneTest
Removed CDATA section support

Others:

- Modified comments
- Implemented tests for Renderer classes