Housekeeping issue, so we don't lost this information.

1. I pinned version of dotnet cli that we install in Pin dotnet-cli version to 1.0.0-preview3-003930 #2573

1. I pinned sha1 commit that we use for downloading dotnet install/uninstall scripts in Fix ci builds #2682

We should un-pin versions, if we can.
It's probably ok to wait until dotnet has the full support for MSBuild and allign this work with transition to .csproj files instead of project.json files.