Package fixes

[bording]

This PR does the following:

• Adds the readme file that is already in the package to the PackageReadmeFile property.
• The AssemblyVersion before MinVer was being set as Major.Minor.0.0, so we need to maintain that as long as we are shipping 0.x packages.
• Works around MinVer adding build metadata to PackageVersion (https://github.com/adamralph/minver/issues/866)