Results 3 issues of nomer

SurfaceGuis appear to render over Decals and Textures, as seen here: ![SurfaceGui Priority](https://cloud.githubusercontent.com/assets/4220749/9535352/56f800ac-4cd5-11e5-93fa-9fdd31fe61bf.png) The only thing I've found that has priority over a SurfaceGui is fully opaque geometry.

Engine
bug

If the Jump property of Humanoid is set to true (by script, jump request, or any other means) when sliding down an unclimbable slope, the player will jump when they...

Engine
bug

This PR implements DataStores v2 APIs. Resolves #22 Some tests are disabled in this branch as they were failing when I forked. Changes: * Implemented metadata API to `MockDataStoreService:GetAsync` and...