Clean up scene node related comments in samples.
Use CMake command to move and rename for portability. Closes #73.

- Revert back CMake version. Use CMake -Wno-dev option to suppress the policy warning for CMake 2.8.12 early adopter.
- Since the new policy is not in place, set some more target property to prevent Urho3D static dependency libs from being transitively link to other targets linking to Urho3D.
Add Lua binding to PODVector<RayQueryResult> and Octree::Raycast()