Remove DirectX11.1 solution configurations

I have removed DIRECTX11_1* and Win8* solution configurations and left only the DX11.2 ones.
Redirected all non-toolkit samples to DX11.2/WinRT output. The Toolkit samples are redirected automatically as now for all WinRT samples the default DX version is 11.2.

Possible additional tasks:

 - [x] Rename solution configuration "Win8DX11_2(Release|Debug)" to just "Win8(Release|Debug)".
 - [x] Rename WP8 output folder to dx11-2 (do we need this?).
 - [x] Test this in Win8 OS and/or with Win8 (non-8.1) SDK - looks like there is a breaking change (https://github.com/sharpdx/SharpDX/commit/903b6e4b1c83db25809b6b0edb02fe30128e0e58).
 - [ ] Test this with the Dev package.
 - [ ] Test this with the installer (I suppose the old build references should be removed).

@xoofx, please review these changes and let me know if it is ok to merge them. Let me know which tasks is worth to do before merging. Integrating D3D9 in DX11.2 build will be done as a separate branch after this one will be merged.