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.
I see what you mean. If the content size type is parent relative, is it possible to determine the correct size during visit and compare this to the size that was last used to alloc the texture / FBO? If the two aren't equal then we destroy and recreate the texture and FBO prior to rendering the render texture / effect node's children? 

I'm guessing there's a situation (or two or three) that I'm overlooking where this won't work. And it would also mean comparing the sizes every frame to see if the texture reallocation needs to happen.