"Any CPU", not "AnyCPU". 

Using the platform "AnyCPU" is a common cause of build failures and confusion. There is no "AnyCPU" platform, only "Any CPU". 

error MSB4126: The specified solution configuration "Release|AnyCPU" is invalid. Please specify a valid solution configuration using the Configuration and Platform properties (e.g. MSBuild.exe Solution.sln /p:Configuration=Debug /p:Platform="Any CPU") or leave those properties blank to use the default solution configuration.
Merge pull request #8 from nathanaeljones/patch-1

"Any CPU", not "AnyCPU".