Added 'NuGet.config file' specifying the NuGet 'packages' folder path.
Updated projects in AutoFixture.sln to reference xUnit.net from NuGet.
Updated projects in Idioms.sln to reference xUnit.net from NuGet.
Updated projects in AutoMoq.sln to reference Moq, and xUnit.net, from NuGet.
Updated projects in AutoRhinoMock.sln to reference Rhino Mocks, and xUnit.net, from NuGet.
Updated projects in AutoFakeItEasy.sln to reference FakeItEasy, and xUnit.net, from NuGet.
Updated projects in AutoNSubstitute.sln to reference NSubstitute, and xUnit.net, from NuGet.
Updated projects in AutoFixture.xUnit.net.sln to reference xUnit.net from NuGet.
Updated CONTRIBUTING.md to reflect the use of NuGet packages.
Removed Moq, RhinoMock, FakeItEasy, and NSubstitute, from Lib folder.
Updated .gitignore in order to include NuGet packages in the source control repository.
Included NuGet packages in the source control repository.
Removed all files from 'xUnit.net 1.6.1' folder except those needed for MSBuild.
Renamed 'xUnit.net 1.6.1' to 'XunitRunnerMSBuild' since this folder now contains only the xUnit.net Runner assemblies for MSBuild.