WebApp-Storage.DotNet.csproj assumes Microsoft.WindowsAzure.Configuration v2.0.0 is in the GAC. If it's not available (or, what's in the GAC is newer), the project fails to build. To make this sample work out-of-the-box, add a reference to Microsoft.WindowsAzure.Configuration:
PS> Install-Package Microsoft.WindowsAzure.ConfigurationManager -Version 2.0.0