React to aspnet/KoreBuild#155

This converts to using Internal.AspNetCore.Sdk instead of importing from the KoreBuild folder directly

NuGet.config

@@ -2,6 +2,7 @@
 <configuration>
   <packageSources>
     <add key="AspNetCore" value="https://dotnet.myget.org/F/aspnetcore-ci-dev/api/v3/index.json" />
+    <add key="AspNetCoreTools" value="https://dotnet.myget.org/F/aspnetcore-tools/api/v3/index.json" />
     <add key="NuGet" value="https://api.nuget.org/v3/index.json" />
   </packageSources>
-</configuration>
+</configuration>

build/common.props

@@ -1,20 +1,17 @@
 <Project>
   <Import Project="..\version.props" />
-  <Import Project="..\.build\common.props" Condition="Exists('..\.build\common.props')" />
 
   <PropertyGroup>
+    <Product>Microsoft .NET Extensions</Product>
     <RepositoryUrl>https://github.com/aspnet/Configuration</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
     <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)Key.snk</AssemblyOriginatorKeyFile>
     <SignAssembly>true</SignAssembly>
     <PublicSign Condition="'$(OS)' != 'Windows_NT'">true</PublicSign>
-    <Product>Microsoft .NET Extensions</Product>
   </PropertyGroup>
 
-  <Target Name="EnsureInitialized"
-          BeforeTargets="Build"
-          Condition="!Exists('$(MSBuildThisFileDirectory)..\.build\common.props')">
-    <Error File="$(MSBuildProjectFile)"
-           Text="Project has not been initialized. Run 'build initialize' in the solution directory '$(MSBuildThisFileDirectory)'" />
-  </Target>
+  <ItemGroup>
+    <PackageReference Include="Internal.AspNetCore.Sdk" Version="1.0.0-*" PrivateAssets="All" />
+  </ItemGroup>
+
 </Project>