I've migrated away from the MSBuild package restore to the automatic package restore which restores packages before the builds begins. (http://docs.nuget.org/docs/workflows/migrating-to-automatic-package-restore)
According to this article http://docs.nuget.org/docs/reference/package-restore-with-team-build TFS 2013 and Visual Studio Online don't need any special configuration, but I've opened up the xaml process templates and they do not implement the NuGetRestore activity. As you can see it's available for use, but I can't find any articles on how to implement it properly.
I've checked all of these templates