Added initial files for repository

This commit includes the following:
* Design.txt : describes goals, steps, questions
* Rendering : contains initial rendering project
* Common : contains the common code required for use of D3DApp

This assumes that the global project settings have the include and
library folders added ONLY for the dx11 sdk, NOT for the Common folder.
The project properties have been modified for this project to point to
THIS common folder in the repository.