updated psake build for nuget
updated psake build for nuget

yonglehou/WebAPIContrib,TerraVenil/WebAPIContrib,andyshao/WebAPIContrib,WebApiContrib/WebAPIContrib,andyshao/WebAPIContrib,modulexcite/WebAPIContrib,WebApiContrib/WebAPIContrib,yonglehou/WebAPIContrib,modulexcite/WebAPIContrib,TerraVenil/WebAPIContrib