Update DependencyModel to the official package and add dotnet-core feed to the NuGet.config

Fix #14.

Author: eerhardt

NuGet.config

@@ -5,8 +5,7 @@
  <clear />
  <add key="nugetbuild" value="https://www.myget.org/F/nugetbuild/api/v3/index.json" />
  <add key="dotnet-buildtools" value="https://dotnet.myget.org/F/dotnet-buildtools/api/v3/index.json" />
- <!-- TODO: https://github.com/dotnet/sdk/issues/14 dotnet-core-test needs to be changed to dotnet-core once the netstandard1.3 DependencyModel package is available -->
- <add key="dotnet-core-test" value="https://dotnet.myget.org/F/dotnet-core-test/api/v3/index.json" />
+ <add key="dotnet-core" value="https://dotnet.myget.org/F/dotnet-core/api/v3/index.json" />
  <add key="api.nuget.org" value="https://api.nuget.org/v3/index.json" />
  </packageSources>
 </configuration>

src/Tasks/Microsoft.DotNet.Core.Build.Tasks.UnitTests/project.json

@@ -1,7 +1,7 @@
 {
  "dependencies": {
  "NuGet.ProjectModel": "3.5.0-rc1-1697",
- "Microsoft.Extensions.DependencyModel": "1.0.1-beta-003393",
+ "Microsoft.Extensions.DependencyModel": "1.0.1-beta-000914",
  "Microsoft.Build.Framework": "0.1.0-preview-00028-160627",
  "Microsoft.Build.Utilities.Core": "0.1.0-preview-00028-160627",
  "xunit": "2.1.0",

src/Tasks/Microsoft.DotNet.Core.Build.Tasks/project.json

@@ -1,7 +1,7 @@
 {
  "dependencies": {
  "NuGet.ProjectModel": "3.5.0-rc1-1697",
- "Microsoft.Extensions.DependencyModel": "1.0.1-beta-003393",
+ "Microsoft.Extensions.DependencyModel": "1.0.1-beta-000914",
  "Microsoft.Build.Framework": "0.1.0-preview-00028-160627",
  "Microsoft.Build.Utilities.Core": "0.1.0-preview-00028-160627"
  },