In Package console, I see next:
Adding Nustache...
Adding 'Nustache 1.15.3.7' to testFrameworcTarget.
Could not install package 'Nustache 1.15.3.7'. You are trying to install this package into a project that targets 'portable-net40+sl50+win+wp80+MonoTouch10+MonoAndroid10+xamarinmac20+xamarinios10', , but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author