Replacing SlimDX with SharpDX in Audio libraries

Dear Cesar,

please find this request to replace *SlimDX* with *SharpDX* in the Audio related Accord.NET libraries (Accord.Audio.Formats, Accord.DirectSound, etc.)

While further development of *SlimDX* seems to have halted, *SharpDX* is still being actively developed and has a lively community. *SharpDX* also offers *WinRT* and *Windows Phone 8* libraries, which facilitates development of Audio support on these platforms via the [PCL flavor](https://github.com/cureos/accord/) of *Accord.NET Framework*.

The *SharpDX* assemblies included in this pull request are unofficial builds of the March 26, 2014, [codebase](https://github.com/sharpdx/SharpDX). It turned out that the latest released version of *SharpDX*, version 2.5.0, contained a few bugs ([here](https://github.com/sharpdx/SharpDX/issues/310) and [here](https://github.com/sharpdx/SharpDX/issues/312)) related to the `SoundStream` class, which is essential for the *Accord Audio* libraries. These bugs were quickly fixed by the *SharpDX* community, but are not yet contained in any official release. Hence the use of unofficial builds here.

I hope that you will find this contribution valuable to the continued progress of *Accord.NET*.

Best regards,
Anders @ Cureos