Data: Add structure for level definitions.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39537
Content: Add sample levels definition.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39538
Game: Add game background.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39539
Game: Draw resizible tiles.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C39540