Remove references inherited via NuGet

These were causing warnings in the error list, as the NuGet build task removes them.

src/ProjectSystem/Microsoft.VisualStudio.ProjectSystem.CSharp.VS.UnitTests/Microsoft.VisualStudio.ProjectSystem.CSharp.VS.UnitTests.csproj

@@ -27,7 +27,6 @@
     <Reference Include="System.Xml" />
     <Reference Include="EnvDTE, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
     <Reference Include="EnvDTE80, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
-    <Reference Include="Microsoft.VisualStudio.ImageCatalog, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
     <Reference Include="Microsoft.Build, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
     <Reference Include="Microsoft.Build.Framework, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
     <Reference Include="System.ComponentModel.Composition" />

src/ProjectSystem/Microsoft.VisualStudio.ProjectSystem.Managed.VS.UnitTests/Microsoft.VisualStudio.ProjectSystem.Managed.VS.UnitTests.csproj

@@ -29,7 +29,6 @@
     <Reference Include="System.Xml" />
     <Reference Include="EnvDTE, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
     <Reference Include="EnvDTE80, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
-    <Reference Include="Microsoft.VisualStudio.ImageCatalog, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
     <Reference Include="Microsoft.Build, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
     <Reference Include="Microsoft.Build.Framework, Version=14.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" />
     <Reference Include="System.ComponentModel.Composition" />