We should publish our NuGet packages to VSTS's artifacts

[eerhardt]

When doing an official build, we only publish our NuGet packages to MyGet. We should also publish them to VSTS's artifacts tab. This way they aren't only on MyGet, and when we push our official packages to nuget.org, we can pull them from VSTS's artifacts drop of the build.

[shauheen]

This is starting to be painful, @artidoro can you please take a look,

Ping @safern @eerhardt