[WinStore] Add check at LoadFromStream method of Texture2D

WIC doesn't not support non-seekable streams.

For example when you load images from the web an exception is throw by
DX but it's not very helpful to identify the problem.

http://sharpdx.org/forum/5-api-usage/379-sharpdx-wic-bitmapdecoder-class-not-working-with-outside-url