Insert NuGet Build 4.4.0-preview1-4434 into sdk

[nugetlurker]

Insert NuGet Build 4.4.0-preview1-4434 into sdk release/2.0-vs branch

[jainaashish]

CC @dsplaisted @nguerrera @livarcocc

[rohit21agrawal]

@dotnet-bot test Ubuntu16.04 Release please

[rohit21agrawal]

@dotnet-bot test
Windows_NT Debug please

[wli3]

@rohit21agrawal our test are looking for nspec, and it is moved, I am fixing the test

[rohit21agrawal]

@wli3 i already fixed the tests

[wli3]

@rohit21agrawal ah, great

[wli3]

@rohit21agrawal looks good. But due to the circular dependency we need to wait for the build of dotnet/cli#7499 and insert it into SDK along with nuget version update

[rohit21agrawal]

i dont think we need to update it every single time.. only when there are breaking api changes in NuGet... is that correct @nguerrera ?

[nguerrera]

Talked offline, we're just going to do it to ensure there are no version mismatches. Sometimes they don't cause issues, but we still need the copies of nuget dlls in the SDK to match the CLI when we ship. Doing it every time makes sure we don't get it wrong. Counting the days until there's just one repo for both and this just goes away. :)

[wli3]

@nguerrera @dsplaisted @johnbeisner FYI i update DotnetCLIVersion to a version that has the new nuget but failed to upload to nuget feed

[wli3]

@MattGertz FYI this is discussed nuget version flow to SDK