Added StudioShell

After watching Pluralsight video, decided to included StudioShell in to
the ChocolateyGUI project, to allow directly calling the psake build
scripts from within Visual Studio, using some new Menu Items added to
the Build Menu, very cool!

Also updated the build scripts that are used.  The MyGet build system has changed, so using both a build.bat and build.ps1 results in a failed build.