Gestures: Redesign.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C41214
Gestures: Add GestureViewModel.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C41215
Logic: Rename GestureSequence to Sequence.

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS15]$/Atomix;C41216