appveyor: avoid websocketpp because that needs Boost
appveyor: avoid websocketpp because that needs Boost

TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm,TyRoXx/cdm