Installing a SharePoint Emulator to unit test CSOM code

I am building an API that uses Sharepoint CSOM to interact with the SharePoint server. I am trying to write unit-tests while mocking the Sharepoint server and I found that the 'Sharepoint Emulator' does that. But when I tried to install the emulator package from Nuget, I am getting the following error:

Failed to add reference to 'Microsoft.QualityTools.Testing.Fakes'. Please make sure that it is in the Global Assembly Cache.

I am using VS2013 Professional.

Can someone please let me know if I can use the emulator with VS2013?