CCEffectNode - Fix a bunch of sizing issues and add tests for them

- Refactor CCRenderTexture's create method into create and createTextureAndFboWithPixelSize. In CCEffectNode, override the create method so pixel size is computed correctly. This fixes effect node's parent relative sizing while leaving render texture the same (because render texture needs even more changes that I don't want to tackle right now).
- Override setContentSizeType on effect node so it also marks the content size as dirty when it changes.
- If content size has changed since the last visit, destroy any allocated resources and recreate them (as CCRenderTexture already does).
- Pass the content size in points to CCEffectRenderer from sprite and effect node.
- Add a bunch of effect node sizing tests.
Thought about this a couple months ago and was sort of avoiding it until it was a problem. If the content size is parent relative then the content size in points can change at any time (even between frames) without any warning or event that can be caught. While somebody might set up a render texture this way, I'm not even sure if there is anything remotely correct we can do.

When put that way, I'm wondering if the only correct thing we can do is to make it an error to use anything but points for the content size type.